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In this study we show the successful deployment of Ground Penetrating Radar (GPR) together with Electrical Resistivity Surveys (ERS) in guiding the archeological excavations at Ashdod-Yam (southern coast of Israel). This approach enabled the precise identification of excavation targets relating to an Early Byzantine ecclesiastical complex located in a residential neighborhood of the modern city of Ashdod. Applied over the course of five years, the combined use of GPR and ERS, interspersed with phases of archeological excavation, not only facilitated an efficient exploration but also ensured the preservation of valuable historical structures. The geophysical data, corroborated by drone images of the post-excavation site, revealed a striking correlation between excavation and non-intrusive survey data. This study not only charts a successful excavation journey but serves as a methodological blueprint for future archeological explorations. The techniques and strategies detailed here have broader implications for the preservation and public presentation of historical sites. [ABSTRACT FROM AUTHOR]

Effective engineering design of structures requires a thorough understanding of the groundwater conditions of the substrate. In some situations, a three-dimensional survey is necessary. Landslides are examples of such cases. They are complex phenomena, and the main factors significantly influencing their behaviour over time are changes in slope geometry, inclination and water conditions. The article discusses the reconnaissance of the substrate structure in an area threatened by mass movements along a modernized section of a railway line. The analysed area is located in the marginal zone of the North Polish glacial moraine. The geological structure of the substrate consists of: glacial tills, glaciofluvial sands, lacustrine clays, and organic soils found in periodically waterlogged areas and depressions in the terrain. Colluvial deposits, mainly consisting of clayey formations, occur on the slope of the escarpment. Surface geomorphology was interpreted using LIDAR data and field observations. Two-dimensional and three-dimensional electrical resistivity tomography (ERT) was used to obtain a detailed subsurface image, which was verified by borehole drilling and laboratory analysis of soil samples for physical properties, including grain size distribution and plasticity, as well as mechanical properties of soils. This research enabled the creation of a three-dimensional substrate model, showing the spatial distribution of colluvium and areas at risk of active landslides. The results indicate that an integrated approach, combining geophysical imaging and geotechnical reconnaissance, allows for a detailed understanding of the structure and lithology of landslide areas.

Geophysical monitoring of CO2 geological sequestration represents a critical technology for ensuring the long-term safe storage of CO2 while verifying its characteristics and dynamic changes. Currently, the primary geophysical monitoring methods employed in CO2 geological sequestration include seismic, fiber optic, and logging technologies. Among these methods, seismic monitoring techniques encompass high-resolution P-Cable three-dimensional seismic systems, delayed vertical seismic profiling technology, and four-dimensional distributed acoustic sensing (DAS). These methods are utilized to monitor interlayer strain induced by CO2 injection, thereby indirectly determining the injection volume, distribution range, and potential diffusion pathways of the CO2 plume. In contrast, fiber optic monitoring primarily involves distributed fiber optic sensing (DFOS), which can be further classified into distributed acoustic sensing (DAS) and distributed temperature sensing (DTS). This technology serves to complement seismic monitoring in observing interlayer strain resulting from CO2 injection. The logging techniques utilized for monitoring CO2 geological sequestration include neutron logging methods, such as thermal neutron imaging and pulsed neutron gamma-ray spectroscopy, which are primarily employed to assess the sequestration volume and state of CO2 plumes within a reservoir. Seismic monitoring technology provides a broader monitoring scale (ranging from dozens of meters to kilometers), while logging techniques operate at centimeter to meter scales; however, their results can be significantly affected by the heterogeneity of a reservoir. [ABSTRACT FROM AUTHOR]

Developing a geophysical test site (GTS) to a full target requires a lot of work in sequential order. This article presents the construction procedures and requirements for developing a GTS, field measurements, geophysical response analyses, and site descriptions. A GTS is an experimental site that contains several targets of known properties, materials, and parameters, buried at different locations, depths, and orientations. The 55 m × 55 m multi-purpose GTS was developed within the Ahmadu Bello University Geophysics Test Site (ABUGTS). The site was developed on a lateritic-clay soil within a shallow depth of 0.6–3 m to study the geophysical signature of various burial scenarios and replicate situations usually encountered in geophysical surveys, engineering, and environmental investigations. A pre-buried investigation with integrated geophysical methods was conducted to provide adequate information about the site condition. The integrated geophysical methods were also explored on a few buried targets for test runs alongside a laboratory test to determine the electrical and magnetic properties of the buried targets. The pre-burial study indicates that the site's electrical resistivity (ER) values decrease significantly from 1081 Ωm to 47 Ωm with depth due to the regional groundwater effect. The post-burial investigations show positive results, corresponding to the laboratory results. The post-burial results show that the subsurface resistivity of the burial terrain decreases from 200 to 0.1 Ωm due to the influence of the buried metallic target and increases from 1081 to 110,000 Ωm due to the influence of the buried non-metallic target, while the total magnetic intensity of the site increases from 44,500 to 48,000 nT. Seismic result shows distortion in subsoil layers after the buried target, confirming a significant influence of the natural geophysical signature of the site by buried targets. The implications of the GTS on economic growth and educational activities were discussed. Geophysicists, researchers, and institutions can now take advantage of the site to explore the existing and new geophysical techniques routinely employed in geophysical investigations. Geophysical equipment manufacturers and individuals can also use the site for instrument configurations. The site can provide an experimental site to appreciate the nature of subsurface anomalous generated by different buried targets. It can serve as a guide for modelling new GTSs while bridging the gaps between hypothetical teaching and real-life problems through effective field-based exercises. [ABSTRACT FROM AUTHOR]

Around 40% of the world's population depends on coastal aquifers for freshwater supply but natural and anthropogenic drivers threaten groundwater availability. Of these drivers, saltwater intrusion (SWI) is one of the most critical and is increasingly affecting coastal areas worldwide. Interest in coastal aquifers has significantly increased, as demonstrated by the growing number of publications in which researchers describe various approaches to illuminate the importance of coastal aquifers, specifically with regard to SWI. The state of research and knowledge of the coastal SWI issue has been reviewed herein. The review includes a discussion of select geophysical and field methods and tools which can inform the numerical modeling of coastal aquifers. MODFLOW was identified as the most often used numerical modeling platform. Further, while many research sites, particularly in the United States, were identified where field studies and geophysical methods, mostly geoelectric ones, added important value to the numerical modeling of the SWI process in the coastal zone, in some regions of the world, data scarcity was identified as the main challenge. Overall, numerical modeling, combined with geophysical methods, is a valuable tool for studying SWI and managing coastal water resources. [ABSTRACT FROM AUTHOR]

The use of geophysical techniques can contribute considerably to the advancement and optimization of subsurface surveys, due to the low costs and time effectiveness. Ground penetrating radar (GPR) has great potential to rapidly and non-invasively evaluate soil in sites affected by the Fundão dam collapse, Southeastern Brazil. The objective of this work was to investigate the thickness of the iron ore tailing layer deposited in a stretch of the Gualaxo do Norte River, besides identifying the most efficient electromagnetic frequency for analysis of this type of material. Three antennas (200, 400 and 900 MHz) were used for GPR surveys in three transects. The radargrams were processed with filtering and gain techniques, aiming to improve the signal quality. We could detect three ground reflection zones with different electromagnetic properties, representing, sequentially, the topsoil, the tailing layer, and the C horizon of the original soil, separated by two reflectors representing the boundaries layers. The tailing layer presented an average thickness of approximately 1 m. 200 MHz presented the best results, whose signal reached the greatest penetration depth and detected the entire tailing layer thickness, besides the others layers present. Using field control points, we could observe that the depths obtained with radargrams had 93% of concordance with the actual depths, which is very satisfactory. The results indicate that the 200 MHz antenna is a better option in surveys involving stratification on Technosols constituted by tailings and GPR should be more explored in the evaluation of soil and sediments. [ABSTRACT FROM AUTHOR]

Abstract With the exploration, development, and research of deep‐sea resources, there is an urgent need for long‐term and continuous observation data of the deep‐sea seabed boundary layer. The traditional method of deep‐sea seabed survey and sampling based on scientific research vessels has the discontinuity of observation data in space and time scales. There are some problems in the seabed in situ observation method based on the seabed observation network for low mobility and high operation and maintenance costs, restricting the in‐depth understanding of the dynamic change process of the deep‐sea floor. To solve the above problems, an open and modular data acquisition control system was designed based on an embedded system and signal processing technology. In terms of the physical, chemical, geological, and ecosystem characteristics of the seafloor or near the seafloor boundary layer, various functional sensors and instrumentation were matched to form an independent underwater integrated measurement or experimental device, eventually realizing in situ multiparameter and long‐time series observations of the seafloor. The system data acquisition and control test were completed through laboratory experiments, which verified the feasibility of the system design. The research showed important theoretical and technical reference significance for the exploration and development of resources in the submarine boundary layer and the promotion of deep‐sea scientific research.

With the exploration, development, and research of deep‐sea resources, there is an urgent need for long‐term and continuous observation data of the deep‐sea seabed boundary layer. The traditional method of deep‐sea seabed survey and sampling based on scientific research vessels has the discontinuity of observation data in space and time scales. There are some problems in the seabed in situ observation method based on the seabed observation network for low mobility and high operation and maintenance costs, restricting the in‐depth understanding of the dynamic change process of the deep‐sea floor. To solve the above problems, an open and modular data acquisition control system was designed based on an embedded system and signal processing technology. In terms of the physical, chemical, geological, and ecosystem characteristics of the seafloor or near the seafloor boundary layer, various functional sensors and instrumentation were matched to form an independent underwater integrated measurement or experimental device, eventually realizing in situ multiparameter and long‐time series observations of the seafloor. The system data acquisition and control test were completed through laboratory experiments, which verified the feasibility of the system design. The research showed important theoretical and technical reference significance for the exploration and development of resources in the submarine boundary layer and the promotion of deep‐sea scientific research. [ABSTRACT FROM AUTHOR]

Around 40% of the world’s population depends on coastal aquifers for freshwater supply but natural and anthropogenic drivers threaten groundwater availability. Of these drivers, saltwater intrusion (SWI) is one of the most critical and is increasingly affecting coastal areas worldwide. Interest in coastal aquifers has significantly increased, as demonstrated by the growing number of publications in which researchers describe various approaches to illuminate the importance of coastal aquifers, specifically with regard to SWI. The state of research and knowledge of the coastal SWI issue has been reviewed herein. The review includes a discussion of select geophysical and field methods and tools which can inform the numerical modeling of coastal aquifers. MODFLOW was identified as the most often used numerical modeling platform. Further, while many research sites, particularly in the United States, were identified where field studies and geophysical methods, mostly geoelectric ones, added important value to the numerical modeling of the SWI process in the coastal zone, in some regions of the world, data scarcity was identified as the main challenge. Overall, numerical modeling, combined with geophysical methods, is a valuable tool for studying SWI and managing coastal water resources.

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This study investigated the Electrical Resistivity Tomography (ERT) A geophysical investigation involving Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) for groundwater potentials in Erhoike Community, Delta State, Nigeria, using standard geophysical methods. Six (6) lithologies including the topsoil, dry sand, saturated sand, clayey sand, sandy clay and clay were delineated within the area. The top soil with resistivity and thickness of 547.5 - 8348.6 ohm-m and 0.7 - 1 m respectively represent the first delineated geoelectric layer. This overlies the dry sand having geoelectric parameter of 3.9 - 19.7 m and 761.4 - 8248.6 ohm-m respectively. The dry sand layer underlain by the saturated sand having resistivity ranging from 114.3 - 1380.6 ohm-m. The resistivity of the clayey sand oscillates between 47.6 - 85.3 ohm-m. This layer represents the last layers at the locations where it was delineated, as such the thickness could not be estimated. The clay layer underlies sandy clay in places while in other cases, it succeeds the topsoil. The resistivity and thickness of the clay layer were 11.4 - 48.9 ohm-m and 25.8 - 56.1 m respectively. The sandy clay was found to have resistivity of 50.6 - 115.3 ohm-m and thickness of 2.9 - 8.8 m. The results of the study showed that the saturated sand layer represents the aquiferous layer within the area where groundwater can be tapped for the community. The thickness of this layer is found to be more than 58.2 m which is quite significant for groundwater development. The study concluded that there is abundance of groundwater accumulation beneath the area. It further reinforced the applicability of combined ERT and VES in groundwater potential mapping in an area underlain by similar geology. [ABSTRACT FROM AUTHOR]

This study investigated the Electrical Resistivity Tomography (ERT) A geophysical investigation involving Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) for groundwater potentials in Erhoike Community, Delta State, Nigeria, using standard geophysical methods. Six (6) lithologies including the topsoil, dry sand, saturated sand, clayey sand, sandy clay and clay were delineated within the area. The top soil with resistivity and thickness of 547.5 – 8348.6 ohm-m and 0.7 – 1 m respectively represent the first delineated geoelectric layer. This overlies the dry sand having geoelectric parameter of 3.9 – 19.7 m and 761.4 – 8248.6 ohm-m respectively. The dry sand layer underlain by the saturated sand having resistivity ranging from 114.3 – 1380.6 ohm-m. The resistivity of the clayey sand oscillates between 47.6 – 85.3 ohm-m. This layer represents the last layers at the locations where it was delineated, as such the thickness could not be estimated. The clay layer underlies sandy clay in places while in other cases, it succeeds the topsoil. The resistivity and thickness of the clay layer were 11.4 – 48.9 ohm-m and 25.8 – 56.1 m respectively. The sandy clay was found to have resistivity of 50.6 – 115.3 ohm-m and thickness of 2.9 – 8.8 m. The results of the study showed that the saturated sand layer represents the aquiferous layer within the area where groundwater can be tapped for the community. The thickness of this layer is found to be more than 58.2 m which is quite significant for groundwater development. The study concluded that there is abundance of groundwater accumulation beneath the area. It further reinforced the applicability of combined ERT and VES in groundwater potential mapping in an area underlain by similar geology.

Metal detection (MD) has traditionally been viewed as a limited geophysical survey method for the identification of metal objects below the surface. However, this pilot study examines techniques utilizing the “ground balance” function, common to most modern metal detectors, to identify subsurface magnetic anomalies. The results of surveys have yielded inconclusive results on the use of metal detectors for feature identification. However, the results of this study suggest a high potential for more efficient and more productive archaeological reconnaissance surveys. The ground balance function, when combined with systematic sampling and geographic information systems interpolation methods, yields low-resolution subsoil magnetic susceptibility maps. Compared to other geophysical methods, such as gradiometry or electrical resistivity, the depth range of MD is limited. However, this technique, in upland contexts with shallow subsoils or sites with high potential for recent ground disturbing activities, can reveal subtle changes in the subsurface that traditional MD techniques would miss. Further studies are recommended to explore the many situations in which a metal detector can provide an informative alternative, though not a replacement, for other geophysical survey methods. This pilot study was funded by the National Geographic Society’s Early Career Grant program.

This article analyzes some aeromagnetic filtering techniques for mitigating deceptive geophysical conceptions that may result in a distorted range of geological information from aeromagnetic data. The implication of using the aeromagnetic method, data processing, and enhancement to distinguish sediment-produced anomalies was considered. Two methods to locate buried faults in aeromagnetic data were compared: Edge and fault detection were considered using the magnetic contrast and horizontal gradient methods, whereas rapid depth estimation was considered using the Euler deconvolution method and Signum method. The general challenge to find the magnetic anomaly depth and delineate edges relies on geophysical filtering techniques discussed in order to maintain its geological relevance. The magnetic-contrast layer model signatures help clarify the existence of intra-sedimentary faults. The horizontal gradient approach relative to other derivative methods has better noise stability and fast adaptation to grids without modifying parameters. However, the Signum transform (ST) approach offers a more special solution in depth estimation than the Euler’s deconvolution approach whose solution relies on the required choice of default shape parameters and windows. The Euler deconvolution procedure may not be able to detect structures found by the ST approach and vice versa. As a result, these techniques may be used in conjunction with one another during analysis, as complementary interpretation tools. This review will however aid in the analysis of information used as a criterion for determining faults using various analytical techniques like ST or Euler deconvolution.

In determining a suitable path and depth for immersing gas pipeline for power generation at Obada Oko, Ogun State Nigeria, a geophysical survey was carried out to assess the characteristics of the subsurface underlying formations for soil corrosivity. The corrosivity of the soil was ascertained by using the soil resistivity values, soil moisture content, and soil pH values. Five Wenner electrical resistivity tomography (ERT) traverses were carried out with twenty soil samples and twenty-four Schlumberger vertical electrical sounding (VES). The result reveals an asymmetric resistivity deviancy along the proposed gas pipeline route, which indicates a mixture of sandy clay to clayey sand deposition laterally and vertically. The soil pH value reveals that the study area was slightly acidic to alkaline and high soil moisture content was observed at traverse four due to its proximity to the Ogun River. The electrical resistivity model reveals that a suitable depth of buried gas pipe must be within the depth of 2.5 to 3.5 m at Traverse (1, 2, and 3) and a depth of 3.5 to 5 m at Traverse (4 and 5). The ERT model reconciles with the soil moisture content at all the traverses chaperoned with the soil pH test. It was concluded that corrosion risk to buried metallic structures at the study zone is almost non-existent and the subsurface is highly competent, yet without proper maintenance, external coating, and cathodic protection, the immersion of gas pipeline could eventually fail. [ABSTRACT FROM AUTHOR]

A measuring instrument is used to measure the insulation resistance of a cable system at a railway control centre. Moreover, online weather data is available as the source of data such as the relative humidity. A data-driven technology can be used for signal detection, signal estimation and signal forecasting. The meaningful characteristics of the data can be extracted by an algorithm so that a relationship is established between the insulation resistance of the cable and the relative humidity. In this way, the remaining lifetime of a cable can be predicted based on the previously observed values. [ABSTRACT FROM AUTHOR]

This study proposed methods based on Sentinel‐2 and Landsat‐8 cross‐fusion for improving water quality mapping (WQM). Therefore, four traditional fusion methods including intensity–hue–saturation, Gram–Schmidt transform, wavelet transform and Brovey transform and different scenarios of cross‐fusion have been implemented. The proposed cross‐fusion methods highly improved the correlation coefficient (CR) between the images and the water quality parameter (WQP). Considering the higher CR values, the created WQP maps showed very good accuracy, in which the root‐mean‐square error values were 0.03, 0.59, 0.96, 0.26 and 279.76 for potential hydrogen (PH), dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD) and electrical conductivity (EC) maps, respectively. Also, the effect of considering 1 px value or the mean of a 3×3 window of the input images for calculating the regression models on the accuracy of the final maps was tested. Only the best outputs for mapping PH and DO parameters were based on applying the mean of a 3×3 window. The results also showed that increasing the window size could increase the computational complexity and decrease the WQM accuracy. Comparing the output maps with the traditional maps confirmed the higher accuracy of the proposed methods. [ABSTRACT FROM AUTHOR]

To assess the rate of sedimentation and the consequent reduction in the storage capacity, periodical capacity surveys of multi‐purpose reservoirs is essential. Hydrographic surveys and acoustic surveys are time‐consuming and expensive. The limited availability and high cost of the high‐resolution images require a different methodology to accurately estimate the water‐spread area of the reservoir. In this study, 30 m resolution hyperspectral image (hyperion) and multi‐spectral image (The Earth Observing One (EO‐1) advanced land imager) are used to estimate the water‐spread area of the Peechi Reservoir, South India. A hybrid genetic algorithm (GA)‐based super‐resolution mapping approach is developed and demonstrated, which incorporates the multi‐objective GA and Hopfield neural network (HNN). The hybrid GA‐based super‐resolution mapping approach gives a global optimum solution in half of the original computation time. Furthermore, mapping approach gives an error of 6.38% for the multi‐spectral image and a lesser error of 3.86% for the hyperspectral image, while the HNN‐based super‐resolution mapping approach gives an error of 8.23% for the multi‐spectral image and 5.71% for the hyperspectral image. Thus, in this work, an efficient technique based on hybrid GA is presented, which is a useful tool for accurate mapping of water bodies at the sub‐pixel scale using hyperspectral imagery. [ABSTRACT FROM AUTHOR]

Subsurface networks include mining tunnels, caves, and the urban underground. Each of these environments presents a complex setting with significant challenges in exploration, exploitation, etc. Multiple hazards exist, including environmental and structural, and conditions degrade and change temporally. We present a survey of research in autonomy, networking and mobility focused on exploring and/or mapping subsurface networks in unpredictable and unexplored environments. The focus is on mining tunnels as a proxy subterranean environment; motivated by the proximity of the authors to the Bonita Peak Mining District; a Superfund site consisting of 48 historic mines which have contaminated soil, groundwater and surface water with heavy metals as a result of historic practices. The exploration and assessment of the mining tunnels for remediation efforts presents an extremely challenging problem in subterranean navigation. Arguably, the environment in question is the most extreme and challenging subterranean environment. Unmanned assets must enter to explore and re-map the tunnels to assess safety for subsequent entrance by robots and/or humans for proper remediation. The survey is split into three categories -- Locomotion, GPS-denied navigation and localization, and Communication. It is concluded with a proposed design for a platform that addresses the difficulties of exploring an abandoned mine

Hyperspecral unmixing (HU) is one of the crucial steps of hyperspectral image (HSI) processing. The process of HU can be divided into end-member extraction and abundance estimation. Lots of abundance estimation methods just take some properties of abundance into consideration, such as non-negative, sum-to-one and so on but ignore the noise corruption. However, in practical applications, there are always high-noise bands in HSI due to water absorption, atmospheric transmission, and other inevitable factors, which lead to the estimation accuracy reduction. Here, we propose a new abundance estimation model which takes the mixing pattern of endmembers and low signal-to-noise ratio (SNR) bands of HSI into consideration simultaneously. The constraints considering not only the low-rank feature of abundance but also the sparsity quality of noise are imposed on the new model for more robust results. Adequate experiments both on synthetic and real hyperspectral data have confirmed the superiority of our method.

The application of ground-based radar to monitor the terrain displacement has attracted more and more attentions recently. Most of the existing ground-based radars utilise a linear horizontal rail where the antennas move to generate the image of the test site. Here, the authors present a topology of antenna array with which the digital elevation model of the observed scene can also be generated besides the 2-D image. Several field experiments have been carried out to evaluate the performance of authors’ developed ground-based differential interferometry radar (GB-DInR) configured with this multiple-input multiple-output (MIMO) antenna array. The results demonstrate that authors’ developed MIMO GB-DInR is able to achieve a sub-millimetre precision of displacement measurement and derive the elevation information of target with an error of

Ground-based interferometry synthetic aperture radar (GB-InSAR) technology is becoming an important terrain mapping technology as it has the characteristics of short observation intervals, flexible operation environment and high data precision. Compared with air/space borne InSAR system, it is much easier for GB-InSAR to acquire repeat-pass/short-baseline data set, which can bring huge convenience on permanent scatterer (PS) technology. By using PS technology, on the one hand, the error caused by low coherence can be avoided, and on the other hand, the speed of the phase unwrapping part can be increased. In order to overcome the disadvantages of the non-uniform PS points distribution and low coherence cavities, the Kriging interpolation method is used to get an uniform digital elevation model (DEM) eventually. This study proposed a GB-InSAR interferogram processing method. First, it proposes a PS point selection method considering both accuracy and efficiency. Second, the study shows a network programming phase unwrapping method to unwrap the PS points. Then, Kriging interpolation method is analysed and used to fill the low coherence cavities. Finally, a field test is carried out in an open pit in Hebei, China. The DEM result of the observation area is shown to verify the correctness of this study's method.

Geosynchronous SAR tomography (GEO TomoSAR) techniques exploit multi-pass SAR acquisitions of the same scene, taken with slightly different view angles, and allow generating fully 3D images. Compared to low earth orbit (LEO) SAR case, GEO SAR has the advantages of shorter revisit time period and wider coverage, which can greatly shorten the data acquisition time, improve the coherence of collected data and effectively improve the 3D imaging accuracy. However, GEO SAR has curved trajectories and un-parallel repeated trajectories, which introduce the along-track component of the spatial baseline. The obtained GEO TomoSAR data based on the data acquisition method using in LEO TomoSAR have the significant rotation-induced decorrelation. Thus, the imaging performance in the elevation is severely degraded. In this paper, we first analyse the feasibility of GEO TomoSAR to achieve 3D imaging. In view of the special issues existing in GEO TomoSAR, we adopt an optimal minimal rotation-induced decorrelation data acquisition method to obtain repeated trajectories data, which can effectively improve the coherence between the collected data. Then, performance of imaging in elevation was analysed based on the spatial baseline distribution. Finally, the feasibility and validity of GEO TomoSAR techniques are validated through computer simulation.

Cloud detection is a fundamental yet challenging topic in remote-sensing image processing. The authors propose a method for multi-dimensional feature extraction and superpixel segmentation, and use a voting-based clustering ensemble to capture the whole target shape. In order to further identify clouds, snow-covered lands, and bright buildings on remote-sensing images, they first implement an Ostu threshold to get high grey-level sub-regions, and then extract the descriptors of these sub-regions and put them into the softmax regression classifier. Regarding these methods, the authors conduct experiments using GF-1 remote-sensing images. The results demonstrate the effectiveness and excellency of their proposed method.

Azimuth multi-channel interferometric SAR (AMC-InSAR) mode integrates the azimuth multichannel high-resolution wide swath (HRWS) imaging technique and high-precision InSAR digital elevation model (DEM) generation technique. More equivalent phase centres are obtained through the azimuth single-input and multiple-output technique, which would provide more azimuth samples. Hence, the reliable and accurate DEM measurement of more wide-swath terrain profile would be obtained. Here, the performance of this AMC-InSAR mode is evaluated theoretically. A new processing method based on measured data for this mode is provided and the results of measured data-processing validate the analysed results and the new method.

As one of the most popular kinds of the component substitution (CS)‐based pansharpening methods, the intensity‐hue‐saturation (IHS) method can produce the pan‐sharpened images with high spatial quality while causing some spectral distortion, mainly owing to it cannot estimate an accurate intensity image in the IHS space. To solve this issue in the IHS method, in this study, the authors propose a new pansharpening method with gradient transferring in the generalised IHS transform space, which aims at estimating a more accurate intensity image. More specifically, the novelty of the proposed method consists of building a novel variational gradient transferring model to transfer the spatial gradient information of the panchromatic image into the new intensity image as well as preserve the local spectral information from the low resolution multispectral image. Finally, they compare the proposed method with some CS methods using the Pleiades, QuickBird, and GeoEye‐1 satellite datasets from both the subjective and objective aspects. Specifically, the experimental results show that the proposed method yields better pansharpening results than the other methods in terms of higher spatial and spectral qualities. [ABSTRACT FROM AUTHOR]

Hyperspecral unmixing (HU) is one of the crucial steps of hyperspectral image (HSI) processing. The process of HU can be divided into end-member extraction and abundance estimation. Lots of abundance estimation methods just take some properties of abundance into consideration, such as non-negative, sum-to-one and so on but ignore the noise corruption. However, in practical applications, there are always high-noise bands in HSI due to water absorption, atmospheric transmission, and other inevitable factors, which lead to the estimation accuracy reduction. Here, we propose a new abundance estimation model which takes the mixing pattern of endmembers and low signal-to-noise ratio (SNR) bands of HSI into consideration simultaneously. The constraints considering not only the low-rank feature of abundance but also the sparsity quality of noise are imposed on the new model for more robust results. Adequate experiments both on synthetic and real hyperspectral data have confirmed the superiority of our method. [ABSTRACT FROM AUTHOR]

The application of ground-based radar to monitor the terrain displacement has attracted more and more attentions recently. Most of the existing ground-based radars utilise a linear horizontal rail where the antennas move to generate the image of the test site. Here, the authors present a topology of antenna array with which the digital elevation model of the observed scene can also be generated besides the 2-D image. Several field experiments have been carried out to evaluate the performance of authors' developed ground-based differential interferometry radar (GB-DInR) configured with this multiple-input multiple-output (MIMO) antenna array. The results demonstrate that authors' developed MIMO GB-DInR is able to achieve a sub-millimetre precision of displacement measurement and derive the elevation information of target with an error of <0.1 m at a distance of around 100 m. [ABSTRACT FROM AUTHOR]

Geosynchronous SAR tomography (GEO TomoSAR) techniques exploit multi-pass SAR acquisitions of the same scene, taken with slightly different view angles, and allow generating fully 3D images. Compared to low earth orbit (LEO) SAR case, GEO SAR has the advantages of shorter revisit time period and wider coverage, which can greatly shorten the data acquisition time, improve the coherence of collected data and effectively improve the 3D imaging accuracy. However, GEO SAR has curved trajectories and un-parallel repeated trajectories, which introduce the along-track component of the spatial baseline. The obtained GEO TomoSAR data based on the data acquisition method using in LEO TomoSAR have the significant rotation-induced decorrelation. Thus, the imaging performance in the elevation is severely degraded. In this paper, we first analyse the feasibility of GEO TomoSAR to achieve 3D imaging. In view of the special issues existing in GEO TomoSAR, we adopt an optimal minimal rotation-induced decorrelation data acquisition method to obtain repeated trajectories data, which can effectively improve the coherence between the collected data. Then, performance of imaging in elevation was analysed based on the spatial baseline distribution. Finally, the feasibility and validity of GEO TomoSAR techniques are validated through computer simulation. [ABSTRACT FROM AUTHOR]

Ground-based interferometry synthetic aperture radar (GB-InSAR) technology is becoming an important terrain mapping technology as it has the characteristics of short observation intervals, flexible operation environment and high data precision. Compared with air/space borne InSAR system, it is much easier for GB-InSAR to acquire repeat-pass/short-baseline data set, which can bring huge convenience on permanent scatterer (PS) technology. By using PS technology, on the one hand, the error caused by low coherence can be avoided, and on the other hand, the speed of the phase unwrapping part can be increased. In order to overcome the disadvantages of the non-uniform PS points distribution and low coherence cavities, the Kriging interpolation method is used to get an uniform digital elevation model (DEM) eventually. This study proposed a GB-InSAR interferogram processing method. First, it proposes a PS point selection method considering both accuracy and efficiency. Second, the study shows a network programming phase unwrapping method to unwrap the PS points. Then, Kriging interpolation method is analysed and used to fill the low coherence cavities. Finally, a field test is carried out in an open pit in Hebei, China. The DEM result of the observation area is shown to verify the correctness of this study's method. [ABSTRACT FROM AUTHOR]

Cloud detection is a fundamental yet challenging topic in remote-sensing image processing. The authors propose a method for multi-dimensional feature extraction and superpixel segmentation, and use a voting-based clustering ensemble to capture the whole target shape. In order to further identify clouds, snow-covered lands, and bright buildings on remote-sensing images, they first implement an Ostu threshold to get high grey-level sub-regions, and then extract the descriptors of these sub-regions and put them into the softmax regression classifier. Regarding these methods, the authors conduct experiments using GF-1 remote-sensing images. The results demonstrate the effectiveness and excellency of their proposed method. [ABSTRACT FROM AUTHOR]

Azimuth multi-channel interferometric SAR (AMC-InSAR) mode integrates the azimuth multichannel high-resolution wide swath (HRWS) imaging technique and high-precision InSAR digital elevation model (DEM) generation technique. More equivalent phase centres are obtained through the azimuth single-input and multiple-output technique, which would provide more azimuth samples. Hence, the reliable and accurate DEM measurement of more wide-swath terrain profile would be obtained. Here, the performance of this AMC-InSAR mode is evaluated theoretically. A new processing method based on measured data for this mode is provided and the results of measured data-processing validate the analysed results and the new method. [ABSTRACT FROM AUTHOR]

• A non-destructive experimental campaign for masonry arch bridges is presented. • The MASW method allowed to characterize the mechanical properties of the infills. • A multidisciplinary method was used to create an accurate numerical model. • The PCE metamodel identified the most sensitive variables of the numerical model. This paper proposes a robust multidisciplinary method that combines geomatic procedures (terrestrial laser scanning and reverse engineering), geophysical methods (ground-penetrating radar and multichannel analysis of surface waves), sonic and impact echo tests, and ambient vibration approaches to generate accurate numerical simulations of masonry arch bridges. These methods are complemented by a robust finite element model updating method based on metamodeling global sensitivity analysis and a robust calibration strategy. The results obtained corroborate the feasibility of the proposed methodology with an average relative error in frequencies of 1.21% and an average modal assurance criterion of 0.93. [ABSTRACT FROM AUTHOR]

A method to estimate frequency domain soil parameters of horizontally multilayered earth is developed. Cole–Cole model of complex conductivity form is adopted to describe the frequency dependence of soil parameters. The estimation of frequency domain soil parameters includes two stages. In the first stage, soil‐layered structure is determined under the DC field by the interpretation of resistivity sounding data. The obtained model parameters in this stage include the DC soil conductivity and thickness of soil layers. In the second stage, Cole–Cole model parameters are estimated based on the soil‐layered model obtained in the first stage. The theoretical formula of complex apparent resistivity is derived from Green's function with considering dynamic‐state field theory. Since dynamic‐state field is considered in the inversion algorithm, this method can be extended into high‐frequency domain. Discrete complex image method is used to calculate Sommerfeld integral quickly. In order to remove electromagnetic (EM) coupling between cables at high frequencies, a new electrode configuration method is proposed. Genetic algorithm is improved by combining with parallel computing. The parallel genetic algorithm is applied to the optimisation of model parameters. [ABSTRACT FROM AUTHOR]

A method to estimate soil parameters of horizontally multilayered earth model in frequency domain is developed with considering high‐frequency field. The theoretical formula of complex apparent resistivity with considering high‐frequency field is derived from Green's function. To avoid time‐consuming numerical integration, complex image method is introduced to solve Sommerfeld integral. Simulated annealing algorithm is applied to optimise soil parameters. The accuracy of this method is confirmed by interpreting field data under the DC field. As the inversion results of this method are different from other literature's results in a four‐layer model, the posterior analysis is made. Then this method is applied to the inversion of frequency domain soil parameters under both quasi‐static field and high‐frequency field. The differences of complex apparent resistivity distribution between quasi‐static field and high‐frequency field are compared at different frequencies. [ABSTRACT FROM AUTHOR]

In this paper, we describe recent studies for the geophysical and geomechanical characterization of soils in Hispaniola (Greater Antilles), an island threatened by the eventual rupture of major seismogenic fault systems. The investigations were performed for four different cities settled on complex geological formations in Haiti (Cap-Haïtien, Port-au-Prince) and the Dominican Republic (Santo Domingo, Santiago de los Caballeros). We present the complete methodology we implemented for mapping zones of homogeneous seismic response and for microzonation studies, but each main stage of investigation is described as it was conducted in one or two cities. Therefore, first we present our site-characterization technique applied to Santo Domingo and Santiago de los Caballeros, which is based on geotechnical data, geophysical multichannel analysis of surface waves, and ambient-noise recordings. Then we present the site-response analysis through numerical analysis with nonlinear soil models that we performed for the city of Cap-Haïtien. Finally, we describe the amplification factors for site-specific response spectra that we derived for the microzonation of Port-au-Prince. We argue for the implementation of a multidisciplinary approach built upon complementary field geological, geophysical, and geotechnical data rather than solely depending on geophysical measures for the characterization of VS30. In addition, we explore the compatibility of the soil classes recommended by the International Building Code (IBC) in the context of local seismic amplification. [ABSTRACT FROM AUTHOR]

Over the last decades, the new non-invasive techniques employed in archaeological research have developed extensively. This article discusses the most important non-invasive surveys undertaken in the Republic of Moldova during the last two decades. Most were carried out in the framework of international partnerships meant to transfer Western experience and knowledge of modern methods of archaeological research to the Republic of Moldova. Special attention is given to the results of cooperation between Moldovan, German and Romanian archaeologists.

Geospatial archaeology is gradually gaining a place of priority in the field archaeology of a variety of archaeological sites during the last decade and a half in India. In accordance with the changing emphasis in the aims and methods of archaeological investigations within and outside the Indian subcontinent and with the availability of scientific and technical expertise in India, application of non-destructive and efficient field techniques has become inevitable. Collaborative research programmes between archaeologists (both Indian and foreign) and experts in geospatial techniques have demonstrated the vast scope of geospatial archaeology in India. Results of such investigations summarized in this article show the efficacy of geospatial archaeology and its potential for ushering a new era of field archaeology in India. [ABSTRACT FROM AUTHOR]

Owing to the ferromagnetism and stray fields of inertial navigation system, component compensation of magnetic field distortion is significant for geomagnetic field vector measurement system. However, traditional scalar compensation methods cannot be used for component compensation of magnetic field distortion, so some improvement works have been researched for component compensation in the study, the major of which is estimating compensation parameters using the Lagrange multiplier method. Experiment results show that the performance of the component compensation method is much better than traditional scalar compensation method. After compensation, the maximal measurement errors of north, vertical, east components and total intensity caused by magnetic field distortion are reduced to 10.4 nT (0.91% of the raw error), 32.5 nT (5.20%), 12.9 nT (1.27%), and 18.4 nT (2.02%), respectively. In addition, compared with previous component compensation method, the proposed method has three advantages: (i) simplified equipment, (ii) easier operation process, and (iii) better generality. [ABSTRACT FROM AUTHOR]

Conventional time‐series interferometric synthetic aperture radar techniques solve elevation correction and linear deformation rate by non‐linear optimisation in 2D space, spatial baseline, and temporal baseline. This letter presents a new method called the time difference baseline set (TDBS). By utilising the discrete characteristic of temporal baseline, the conventional 2D optimisation can be transformed into two 1D optimisations to estimate elevation correction and linear deformation rate, respectively. The authors' TDBS‐based two‐steps method reduces the time complexity from O(n2) to O(n) without compromising on accuracy. The comparative experiments and analysis carried out on real data confirmed the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]