Search

The study of ancient Egyptian monuments attracts the attention of experts from around the world. A recent event that confirms this is the discovery, using muon sensors, of previously unknown cavities in the Great Pyramid of Giza (or Khufu's Pyramid). Since it is unfeasible to directly confirm this discovery by drilling, another independent non-destructive method is necessary to confirm this discovery and provide accurate determination of the locations and shapes of the cavities. Following a literature review of the different methods used in evaluating cultural objects, this paper analyses a possible framework for simulation of a holographic radar for detecting openings or other unknown structures of interest to archaeologists/Egyptologists and the public.

This article generalizes Bechtel and Bechtel (2020a, 2020b). The results in these papers induce our hypotheses that GDP predicts income and survival. These hypotheses are confirmed at the global level and we invite the G20 to confirm them at the national level as well. Our regressions show that global life expectancy and global gross income per capata can be predicted from GDP alone without survey sampling, questionnaire interrogation, probabilistic inference, or significance testing. In view of trade-war and COVID-19 shocks to the world economy,international attention to GDP’s life-saving effects is now compelling.

Bechtel (2018, 2019) linked gross domestic product (GDP) to the United Nation’s Human Development Index (HDI). These results at the national level, and subsequent results at the global level (Bechtel, G. and Bechtel, T., 2020), induce our hypothesis that a transform of American GDP predicts global HDI. This hypothesis is confirmed by two distinct bilinear regressions in which global HDI is predicted by American GDP alone. These empirical findings contribute to the socioeconomic and philosophical debate on the nature of well-being. They also show that HDI computation can be carried out from American GDP without survey sampling, questionnaire interrogation, probabilistic inference, significance testing, or even HDI data. In view of trade-war and covid-19 shocks to all national economies, international attention to American GDP is now compelling.

This article presents a new UWB impulse radar system consisting of a central radiating antenna (1.9-GHz center frequency, 2-GHz bandwidth) and four receiving antennas designed for the detection and location of dielectrically large objects with dimensions comparable to the spatial dimensions of the probe pulse. Together with the radar system, a solution method for determining the coordinates for detected targets is developed based on the time of flight (TOF) of the probing pulse along raypaths from the radiating antenna to the object, and then reflected to each of the receiving antennas. An algorithm based on the Pearson’s correlation coefficient is used to accurately determine the TOF of the signals scattered by the object. The antenna geometry makes it possible to use simple trigonometry and Heron’s formula, to calculate the coordinates of the reflecting bright spot on a target. The algorithm has been tested by numerical simulations and experiments with a cylindrical metallic object (diameter 10 cm) and a plastic-cased PMN-2 landmine buried in natural clay soil. For the experiment, GPR signals were acquired on a $4 \times 4$ square grid at 10-cm step from a height of about 30 cm above the ground. The system detected the test object in all positions and the positioning error in majority is equivalent to the object size.

The American Federal Reserve’s Board of Governors has been negotiating with the Congress in order to add a third mandate to their longstanding missions of reducing unemployment and inflation. Chairman Powell described this mandate as the mitigation of shrinking GDP. We model this mandate by two axioms, which reveal American GDP as the sole driver of global GDP. The close fit of each model demonstrates that axiomatic venture can discover and corroborate truth via distinct pathways. In view of trade-war and pandemic shocks to GDP worldwide, this third mandate is now compelling. Congressional inaction will reduce global livelihood in a post-pandemic era (https://www.federalreserve.gov/newsevents/testimony/powell20190710a.htm).

Bechtel (2018, 2019) linked gross domestic product (GDP) to the United Nation’s Human Development Index (HDI). Bechtel, G. and Bechtel, T., 2020 then found that American GDP alone predicted HDI. These results induce the hypotheses that two transforms of GDP perfectly predict a new index of HDI-attenuated GDP (W) introduced here. These hypotheses are confirmed at the global level and for the United States and China, the world’s two largest economies. These discoveries inform the debate on well-being and show that W can be computed from GDP without survey sampling, questionnaire interrogation, probabilistic inference, or significance testing. In view of trade-war and COVID-19 shocks to the global and national economies, international attention to GDP and human development is now compelling.

This article extends results reported by Bechtel, G. and Bechtel, T. (2021). These previous findings induce the hypothesis confirmed here; namely, that gross domestic product GDP nearly perfectly predicts survival in the world’s entire population. The fractional polynomial regressions here are run over the pre-pandemic period 1991–2016. During the subsequent pandemic, the American Center for Disease Control reported that life expectancy at birth in the USA dropped one year during the first six months of 2020, the largest drop since World War 11. The drops in African and Hispanic life expectancy at birth during this period were 2.7 and 1.9 years (Aljazeera; Democracy Now, February 18, 2021). The USA is the worst covid-19-effected population. It is now imperative to confirm that life expectancy at birth is well predicted from GDP in all nations over 1991–2018. This pre-pandemic control for each nation will accurately calibrate it’s subsequent yearly survival drops due to Covid-19. This is especially important in light of the trade war between the United States and China, which has increased the need for accurate measurement of the human effects of this war.

(IF 6.44; Q1); International audience; Karst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset’s coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations.

This paper contains a review of various radar systems that are designed for the detection of landmines. The main principles of their operation, their methods of application, and their achievements are considered. We review both functioning systems and prospective future systems.

This paper discusses a technique for automatic detection of subsurface objects using the impulse UWB radar of the "UGO-1st" robotic platform. The method is programmed as a Web application with capabilities for flexible adjustment of data processing parameters by the user. It provides reliable detection without false alarms and with correct calculation of coordinates for shallow buried subsurface objects.

Karst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset’s coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations., Measurement(s)hydrographic feature • fluid flow rateTechnology Type(s)digital curationFactor Type(s)geographic location • yearSample Characteristic - Environmentkarst • spring • groundwater Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11336507

This paper covers advances made in the tripwire detection aspect of the Landmine Detection 4.0 project. This includes algorithmic improvements - most importantly a comparison between a gradient-sigmoid filter and a derivative subtraction filter - and testing of these algorithms on tripwire scenes. We used a Canon DSLR camera for testing, which provides higher resolution and a different spectral range than the FLIR thermal camera we had used in previous testing. We have also begun investigating the use of near-infrared cameras as a possible alternative. Additionally, we have investigated methods to reduce false-positive detections within images with the intention to implement and test some of these methods in the near future.

A new generation of instruments capable of detecting plastic landmines aims to increase operator safety and productivity for humanitarian demining. The complex environmental conditions require the measurements of several physical parameters to enhance the detection of plastic and metal landmines by metal detectors and ground penetrating radars mounted on a robotic platform. The architecture of the multisensor robotic platform, based on the Industry 4.0 paradigm, is described, and an example is provided which describes how to exploit the multiple sensor information with experiments carried out in a test bed with landmine simulants.

Holographic subsurface radar (HSR) is not currently not in widespread usage. This is due to an historical perspective in the ground penetrating radar (GPR) community that the high attenuation of electromagnetic waves in most media of interest, and the inability to apply timevarying gain to the continuous wave (CW) HSR signal precludes sufficient effective penetration depth. While it is true that the fundamental physics of HSR, with its use of a CW signal, does not allow amplification of later (i.e. deeper) arrivals in lossy media (as is possible with impulse subsurface radar — ISR), HSR has distinct advantages. The most important of these is the ability to do shallow subsurface imaging with a resolution that is not possible with ISR. In addition, the design of an HSR system is simpler than for ISR due to the relatively low-tech transmitting and receiving antennae. This paper provides a review of the main principles of HSR through an optical analogy and describes possible algorithms for radar hologram reconstruction. We also present a review of the history of development of systems and applications for HSR of the “RASCAN” type which is possibly the only commercially available holographic subsurface radars. Among the subsurface imaging and remote sensing applications considered are humanitarian demining, construction inspection, nondestructive testing of dielectric aerospace materials, surveys of historic architecture and artworks, paleontology, and security screening. Each application is illustrated with relevant data acquired in laboratory and/or field experiments.

To protect karst spring water resources, catchments must be known. We have developed a method for correlating spring hydrographs with newly available, high-resolution, satellite-based Global Precipitation Measurement data to rapidly and remotely locate recharge areas. We verify the method using a synthetic comparison of ground-based rain gage data with the satellite precipitation data set. Application to karst springs is proven by correlating satellite data with hydrographs from well-known springs with published catchments in Europe and North America. Application to an unknown-catchment spring in Pennsylvania suggests distant recharge, requiring a flow path that crosses topographic divides, as well as multiple lithologies, physiographic provinces, and tectonic boundaries. Although surprising, this latter result is consistent with published geologic/geophysical, monitoring well, and stream gage data. We conclude that the method has considerable potential to improve the speed and accuracy of catchment identification and hydrodynamic characterization, with applications to water resource protection and groundwater exploration, among others.

Peatlands are valuable but fragile ecosystems with diverse biogeochemical and hydrological functions, so their characterization requires non-destructive investigation. We studied adjacent alpine peatlands of similar size, at the same altitude, and exposed to identical climatic conditions, but with differing topographic and geologic settings producing contrasting ecohydrological functioning; one is a rainwater-fed bog, the other is a groundwater-fed fen. Two intentionally simple geoelectrical techniques were applied to obtain rapid geophysical fingerprints of these peatlands: vertical electrical sounding (VES) and self-potential (SP). Strongly contrasting results agree with conceptual understandings of bogs and fens. The bog VES displays a high-resistivity near-surface layer, corresponding to lowly-mineralized rainwater, while resistivity in the fen is two orders of magnitude lower due to more highly-mineralized groundwater. The SP profile of the bog indicates radially-divergent drainage, while the profile of the fen points to lateral groundwater inflow from adjacent slopes. The paired-peatland approach made possible identification and isolation of the effects of hydrological functioning on geophysical properties, while eliminating possible differences due to climate or altitude. Most importantly, this study shows that very few and simple geophysical measurements can produce critical near-real-time data on hydrologic properties of peatlands – which is especially important for inaccessible high alpine locations.

Accidents during spacecraft launching quite often occur in different countries. They cause considerable direct material losses and indirect losses in the form of increased premiums for the insurance of subsequent launches. One of the means to improve reliability of the rockets is the non-destructive testing of the manufactured products. This paper focuses on introduction of a new holographic subsurface radar technology as a nondestructive testing technique of dielectric materials and comparison of this technology with X-ray and ultrasonic methods.

Field tests of the robotic platform “UGO-1st” have revealed interference sources that complicate the automatic detection of subsurface objects by UWBGPR. Although robust target discrimination criteria make it possible to reduce the probability of false alarms, identification of these sources of interference improves the detection algorithm. The focus of this work is on the elimination of interference sources, which include: direct coupling between radar antennas; reflections from components of the robotic platform; reflections from the soil surface; instability of the GPR signal due to temperature drift during a scan. To reduce these effects we performed measurements with the robotic system suspended in air high above the ground so that signals from any subsurface reflection would arrive long after the signals from the robot structure that are to be identified and removed. These signals are also used to compensate for temperature drift, as well as to remove signals from direct coupling between antennas. The procedure for the background removal includes: selection of a time window before the reflection from surface; an optimization procedure for determining the time drift caused by temperature changes; alignment of the two signals; and subtraction of the background signal from the received one. This is performed for all four receiving channels separately. The need to remove reflections from the soil surface is due to the fact that these signals arrive at the receiver almost simultaneously with the reflections from shallow buried objects. This makes it difficult to determine the arrival time of the reflected signal. Reflections from the soil surface can also be eliminated in a manner similar to the one mentioned above but instead of measuring a background signal we took signals collected a few cm ahead of a known target. The algorithm was applied to real data and has proven to be effective.

The main goal of this project is to demonstrate the advantages of sensor integration on a remotely controlled robotic platform for increasing operator safety and improving the classification of explosive targets. This is accomplished by combining the imaging provided by radars and an optoelectronic sensor, a time-of-flight (ToF) depth camera. An additional aim is to demonstrate the operability and practicality of the system in a field with landmine simulants having plastic cases.

As reported in previous chapters, the “Advanced Research Workshop on Explosives Detection” (the Workshop) represented an important gathering of scientists, engineers, policy-makers, and administrators working within the framework of the NATO Science for Peace and Security (SPS) Programme. The three pillars of SPS are Science, Partnership, and Security, and this workshop thoroughly embodied all three in ways that will be discussed in this chapter. However, participants also identified avenues to strengthen these pillars – especially in Partnership – and we reserve discussion of this pillar for last.

To design holographic and impulse ground penetrating radar (GPR) sensors suitable for humanitarian de-mining in the Donbass (Ukraine) conflict zone, we measured critical electromagnetic parameters of typical local soils using simple methods that could be adapted to any geologic setting. Measurements were recorded along six profiles, each crossing at least two mapped soil types. The parameters selected to evaluate GPR and metal detector sensor performance were magnetic permeability, electrical conductivity, and dielectric permittivity. Magnetic permeability measurements indicated that local soils would be conducive to metal detector performance. Electrical conductivity measurements indicated that local soils would be medium to high loss materials for GPR. Calculation of the expected attenuation as a function of signal frequency suggested that 1 GHz may have optimized the trade-off between resolution and penetration and matched the impulse GPR system power budget. Dielectric permittivity was measured using both time domain reflectometry and impulse GPR. For the latter, a calibration procedure based on an in-situ measurement of reflection coefficient was proposed and the data were analyzed to show that soil conditions were suitable for the reliable use of impulse GPR. A distinct difference between the results of these two suggested a dry (low dielectric) soil surface, grading downward into more moist (higher dielectric) soils. This gradation may provide a matching layer to reduce ground surface reflections that often obscure shallow subsurface targets. In addition, the relatively high dielectric deeper (10 cm–20 cm) subsurface soils should provide a strong contrast with plastic-cased mines.

As of 2017, there are an estimated 100 million abandoned land mines littered across 61 countries. Following the wars in Afghanistan, Libya, Syria, Yemen, and Ukraine, there has been a rise in casualties due to the triggering of previously-abandoned explosive devices. The above institutions combined specialties to develop a remotely-operable, multisensor, robotic device for the detection of land mines, UXO (1), and IEDs (2). The robotic detection device uses novel subsurface radar with imaging and target classification to differentiate between threatening landmines and innocuous clutter. The expected outcome of this research is the creation of a multi-sensor system on a semi-autonomous vehicle for detection and discrimination of explosive devices. This robotic platform will change the approach to detecting landmines in post-war zones, all the meanwhile lessening direct human-to-mine or animal-to-mine contact in detecting landmines. Architecture has a high potential to move the procedures of explosive detection toward completely remote and autonomous system.

In a joint project, research partners across institutions combined specialties to develop a remotely-operable, multi-sensor, robotic device for the detection of land mines, unexploded ordnance (UXO), and improvised explosive devices (IEDs). The robotic detection device uses a novel subsurface radar with imaging and target classification to differentiate between dangerous landmines and harmless clutter. One important aspect of this project has been to develop a system for imaging the terrain and potential obstacles ahead of the moving vehicle. Three important tasks drive the need for this look-ahead imaging: obstacle avoidance, tripwire detection, holographic subsurface radar (HSR) image correction.

The modern world is characterized by the pervasive use of computers, sensors, robotics, and Internet connectivity. This represents a new industrial revolution, dubbed Industry 4.0. In this paper, we discuss the application of the Industry 4.0 paradigm to creating a robotic search-and-detection platform intended for humanitarian demining. This is based on the combination and interaction of two microwave radars - including a UWB multi-sensor array, and a holographic imager - as well as 3-D optical cameras, remote navigation, and GPS tracking. The concepts introduced by Industry 4.0 represent an important opportunity for the scientific community to adopt new approaches in the design and use of UWB radar systems, and how data from these systems can be shared, archived, and processed in a decentralized manner accessible to the worldwide community

We have developed a stand-off holographic subsurface radar (HSR)operating at 2 GHz with amplitude and phase outputs for detection and classification of buried shallow objects, including plastic landmines. The microwave holograms obtained in this way contain information about the size and shape of the buried objects within the penetration depth. The reconstruction of the electromagnetic field on a plane parallel to the scanning plane has been repeatedly addressed in the literature; however, the propagation of the incident field through the air-soil interface generates a refracted path into air and soil with a different velocity and thus results in different phase changes. Furthermore, the actual dimensions of the antenna aperture in relation to the scanning surface and the real radiation pattern are to be considered. In this work, we define and test an algorithm that uses the amplitude and phase data derived from the use of a finite-sized monostatic antenna. The antenna, with an aperture comparable to the buried object size (circular aperture of 11.5 cm of diameter), is positioned at few centimetres from the ground, and scans an area containing the buried object to provide the basic hologram. We have investigated the proposed method to assess the improvement in the detection of buried objects.

Geothermal energy can be used for heating, electric power generation and other applications (e.g. Seyboth et al. 2008). The confidence of the public in this technology is currently compromised by several bad examples where inappropriate implementation of geothermal installations has caused avoidable damage. A dramatic but instructive case is presented here. This article is a plea both for the reasonable use of geothermal energy and for more geologic and hydrogeologic competence and education in geothermics. Connoisseurs of classical German literature know the historic town of Staufen (7,800 inhabitants; Fig. 1) as the town of Doctor Faust, immortalised by the eponymous drama written by Johann Wolfgang von Goethe (1749– 1832). The town is currently suffering severe damage that began immediately following geothermal drillings in the city centre. Staufen is located in the Upper Rhine Graben, within the tectonic transition zone between the central graben and the Black Forest. The graben is filled with several kilometres of sediments; the Black Forest mainly consists of crystalline rocks. In the transition or foothill zone (German: Vorbergzone), Mesozoic sedimentary rocks are present below the surface or crop out as ridges and hills, reflecting the fault pattern and tilting of the strata. In this region, the Upper Triassic (Keuper), which is also present below Staufen, includes gypsum and anhydrite layers and lenses of substantial thickness, which is common knowledge and documented in publications and geologic maps. Even a standard German-language textbook entitled Geologie von Mitteleuropa (Geology of Central Europe) mentions noteworthy anhydrite occurrences in this region (Walter 1992). Anhydrite transforms into gypsum when it comes in contact with water, resulting in a volume increase of up to 61% that can generate pressures of 5–10 MN/m. Geotechnical engineering books, including traditional German textbooks, discuss this problem and recommend avoiding any contact between anhydrite and groundwater in all types of construction activities (Prinz 1991). There are numerous well-studied examples, internationally and in southwest Germany, where swelling of anhydrite caused severe geotechnical problems during construction of roads, tunnels or buildings. In the USA alone, an oftcited study by Jones and Holtz (1973) calculated that shrinking or swelling materials inflicted at least $2.3 billion USD annually in damage to houses, buildings and roads. This geologic and geotechnical knowledge appears to have been ignored during the Staufen project, and a predictable disaster has run its course. In late 2007, seven boreholes, up to 140 m deep, were drilled into the gypsumand anhydrite-bearingKeuper formations, creating hydraulic contact between anhydrite and confined groundwater. The boreholes were cased in the uppermost part, while the deeper parts remained uncased. A few weeks after drilling, cracks started to form in nearby buildings. Geodetic measurements soon revealed that the ground was rising. Since then, the impacted area has increased steadily; 131 houses are currently affected, with some houses seriously damaged (Fig. 2). The highest uplift exceeds 1 cm/month, with no signs yet of slowing. The uplift rate and the degree of damage generally decrease with increasing distance from the drillings (statement to the press, released in December 2008 on the website of Staufen, www.stadt-staufen.de). One type of crack is particularly prominent and frightening: vertical, open cracks that seem to be oriented towards the area of the drillings and tend to cut the impacted buildings from the ceiling to the roof (Fig. 3). It is conceptualised that these types of radially divergent, vertical cracks also exists underground, caused by serious swelling of a cylindrical zone around the drillings. At the N. Goldscheider ()) Centre of Hydrogeology (CHYN), University of Neuchâtel, Rue Emile-Argand 11, 2009, Neuchâtel, Switzerland e-mail: nico.goldscheider@unine.ch Tel.: +41-32-7182645

In recent years, microwave methods for nondestructive testing (NDT) as an alternative to conventional ultrasound techniques, are becoming more common in the aerospace industry. Microwave sensors are applied to the examination of composite materials and structures which have many advantages over, and are replacing, traditional metal alloys. Composites typically have a better strength-to-weight ratio, and can withstand adverse weather conditions and corrosive environments. Such materials include polyurethane foam (PUF) insulation, silica fiber tiles (which were used for thermal protection in the American Space Shuttles and the Soviet spacecraft “Buran”), and honeycomb fiberglass which is frequently used in airplanes. The American and Soviet reusable launch system, and other space rockets, which fly on cryogenic fuel components, use PUF insulation to prevent both boiling-away of these components during prelaunch preparation, and the formation of surface ice which can damage the construction. The Space Shuttle Columbia catastrophe showed that PUF insulation coatings require diligent quality control during manufacture and use. Due to the high level of acoustic wave attenuation in porous composites, conventional ultrasonic diagnostic methods are ineffective for these materials, and holographic subsurface radar may be the best alternative. This work describes the development of a special experimental setup consisting of a vector network analyzer, used for signal generation and reception, and an electromechanical scanner which precisely moves the studied samples. The operating frequency band of the vector network analyzer allows experiments across a wide waveband up to 24 GHz. For registration and reconstruction of complex multifrequency microwave holograms, specialized software was developed. The software has special functions for improving quality of reconstructed holograms and suppressing reflections from samples borders. The setup was used for investigation of the operating frequency influence on subsurface imaging results. All of the samples contained intentional model defects typical of composite materials. Comparison of blind experimental imaging results for these test samples with maps of defects (revealed post-experiment) showed good agreement, proving effective detection and delineation of hidden flaws.

This paper reports on an experimental study of object detection and location using UWB Impulse GPR with a specialized “1Tx and 4Rx” antenna system. Algorithms for data collection and processing are described. The results of the study demonstrate the ability of the radar to cover a lane width of more than 60 cm with the antenna array at a height of 37 cm. Within the lane the system can readily detect an antipersonnel landmine simulant. Preliminary analysis of laboratory testing data (in air) has also shown the capability of the proposed processing to estimate the distance between the object and each Rx antenna with an accuracy of 0.8 cm for distances up to approximately 40 cm.

We are designing and building a multi-sensor semi-autonomous vehicle to assist in humanitarian demining in the Donbass conflict zone, Ukraine. The vehicle will carry impulse GPR for fast target detection, and holographic GPR for discrimination of mines from clutter. The design includes the possibility to add additional sensor. To ensure that the vehicle is compatible with actual Donbass conditions, the COTS dimensions of the selected vehicle (Clearpath Robotics “Jackal”), and relief profiles from two transects collected on the edge of the conflict zone, were compared using morphological filtering terrain analysis. The analysis shows that the vehicle can traverse the recorded transects with no threat of nose-in failure, and minimal threat of hang-up failure. Preliminary testing of the holographic radar mounted on the vehicle show that it can effectively image the footprint of mine-like targets, with resolution of a little more than one centimeter.

Analysis of critical conditions on the reusable spacecrafts Columbia (USA), and Buran (Russia) related to defects in insulation and heat-protection coatings have been performed. It is shown that the existing methods of non-destructive testing, including ultrasonics, failed to prevent the disaster of the Space Shuttle Columbia and serious incidents involving the spacecraft Buran during its only flight. A new method for using the holographic subsurface radar RASCAN-5/15000 which reveals the internal defects of the coating was proposed, and experiments on models of thermal insulation coatings were performed. The experimental results were displayed in the form of radar images on which defects in the heat insulation provided a good contrast. The article reflects preliminary study and further efforts are needed to improve resolution of the technology.

This paper describes the development of an impulse GPR configuration suitable for the detection of buried targets in natural soils - particularly the Eastern Ukraine conflict zone. The design has incorporated the requirements for a lightweight and compact system to be installed as a one component of a multi-sensor robotic scanner. The antennae have been placed in a configuration such that the footprint at 2 GHz remains sufficiently large to scan an area with dimensions larger than a typical plastic- or metal-cased landmine. The target detection and positioning algorithm, based on recorded time-of-flight data has been developed for this configuration and the analytical solution is essentially real time, simple, and easily implemented on low power ARM processors.

Dinosaurs are an interesting group of ancient animals, the study of which can give valuable information about the evolution of life on the Earth. Study of their fossilized tracks can provide information not only about these animals' morphology, but also their behavior. Until now, research has been limited to dinosaur tracks and trackways fortuitously exposed on rock surfaces. The use of subsurface imaging radar provides the potential to detect tracks that remain hidden by younger strata in cases where a dielectric contrast exists between the layers, or a dielectrically anomalous film separates the track mold from overlying cast. In this paper the possibility of using the method of holographic subsurface radar to detect hidden tracks of dinosaurs is investigated. Research was carried out under laboratory conditions on a gypsum plaster mold and cast of an Anamoepus track using a radar scanning system operating in different bands at centimeter wavelengths.

This paper discusses modern requirements for, and approaches to, design of a multi-sensor robotic radar system for humanitarian demining, and a through-wall imaging radar. In addition, we review progress in use of UWB radar systems for investigation of objects and structures representing important historical and cultural heritage. A review of the special European action intended for progress in civil application of UWB radar is also presented.

In order to design holographic and impulse GPRs, as well as metal detector (MD) sensors for humanitarian demining in the Donbass conflict zone, we have compiled a listing of the AP and AT mines that have been confirmed in use in Donbass, and their dimensions and construction. Just as importantly, we have attempted, from existing literature (since it is an active war zone), to characterize the specific soils in this region in order to understand the physical property contrasts between mine casings/components and the soils in which they may be buried, as well as the propagation characteristics of radar signals in these soils. We conclude that MD should be generally effective for locating Donbass mines, and GPRs operating near the frequency of 2GHz should provide sufficient penetration for detection and, simultaneously, sufficient resolution to assist with discrimination of mines from clutter. As is common in GPR applications, the main limiting factor may be soil moisture content, so operations may be restricted to dry periods or seasons. Field measurements are scheduled to confirm the values from the literature.

Holographic subsurface radars (HSR) are not in common usage now; possibly because of the historical view amongst radar practitioners that high attenuation of electromagnetic waves in most media of interest will not allow sufficient depth of penetration. It is true that the fundamental physics of HSR prevent the possibility to change receiver amplification with time (i.e., depth) to adapt to lossy media (as is possible with impulse subsurface radar or ISR). However, use of HSR for surveying of shallow subsurface objects, defects, or inhomogeneities is an increasingly proven area of application. In this case, HSR can record images with higher resolution than is possible for ISR images. The RASCAN family of holographic radars is presented along with technical specifications and typical case histories. Among the applications considered are civil and historic building surveys, nondestructive testing of dielectric materials, security applications, and humanitarian demining. Each application area is illustrated by relevant data acquired in laboratory experiments or field tests. This paper presents experiments with RASCAN imaging in media with different degrees of attenuation, and illustrates the principle of HSR through an optical analogy.

This paper describes a new application of holographic radar for non-destructive testing applied to cultural heritage items. A holographic radar, called RASCAN, operates in continuous wave multi-frequency mode at 4 GHz range and produces images with high in-plane resolution (about 2 cm). Marble items and other stones have been investigated to validate the method to search for subtle cracks, moisture or to unveil details of structures at shallow depth (up to 2 wavelengths). Other important materials are aged wood items that are investigated for tunnels made by insects. Then the holographic radar imaging has been experimentally compared with infrared thermography to understand the advantages and disadvantages of these methods and to derive indications for solving the problem common in all geophysics of inherent non-uniqueness.

This paper explores the application of the RASCAN holographic radar for non-destructive subsurface imaging of works of art and architecture. This radar provides high-resolution plan-view images of the shallow subsurface in dielectric materials. The radar is particularly sensitive to small metallic targets, but also to variations in moisture content. Originally developed for detection of hidden bugging devices, sounding of building construction details, and detection of landmines, here the utility of the RASCAN radar for art and architectural preservation studies is demonstrated by several bench-top experiments on stone and wood items with different subsurface defects and features, as well as actual field tests on a decorative marble medallion in the floor of the Temple of San Biagio in Montepulciano, Italy, and Frescoes in the Church of San Rocco in Cornaredo, Italy. Historical research indicates that the medallion in San Biagio was laid circa 1590 during the funeral ceremony of a Prelatio of the family Casata Cervini. The actual burial place of the Prelatio is not recorded, but a radar scan of the medallion, and follow-up scans of a bench-top model suggest the possibility of a cavity that could contain remains or relics. In San Rocco, small delaminations were detected behind the frescos. Copyright © 2009 John Wiley & Sons, Ltd.

A subsurface holographic radar using a multi-frequency signal has been developed for inspecting dielectric construction materials. The characteristic feature of this device is the ability to obtain one-sided radar soundings/images with a high sensitivity and high resolution (2cm) in the frequency band of 3.6{4.0GHz. One promising application of the device is non- destructive evaluation of the heat protection system and other materials on the U.S. Space Shuttle, and proposed crewed exploration vehicle (CEV). The advantages of this continuous- wave holographic radar over traditional impulse subsurface radars are discussed and illustrated by experimental results. The disastrous loss of the space shuttle Columbia, as well as even more recent dangerous incidents that were thankfully resolved, have aroused interest in possible new methods and devices for non- destructive testing and evaluation of the Space Shuttle Thermal Protection System, the external fuel tank insulating foam, and other materials and structures on the shuttle (see Figure 1), proposed CEV, and other space vehicles. Voids in or under the external tank insulating foam are considered potential sites for \cryopumping" where water seeps in and then evaporates explosively at altitude, pulling the foam from the tank (Figure 2). One of the possible means for non-destructive testing (NDT) and evaluation of structural ma- terials is subsurface radar. This method is based on the propensity of electromagnetic waves to be re∞ected at permittivity contrasts. Up to now, the use of radar for NDT has been hindered by