Ground‐Penetrating Radar for Close‐in Mine Detection

In this chapter, two of the major challenges in the application of ground‐penetrating radar in humanitarian demining operations are addressed: (i) development and testing of affordable and practical ground penetrating radar (GPR)‐based systems, which can be used off‐ground and (ii) development of robust signal processing techniques for landmines detection and identification. Different approaches developed at the Royal Military Academy in order to demonstrate the possibility of enhancing close‐range landmine detection and identification using ground‐penetrating radar under laboratory and outdoor conditions are summarized here. Data acquired using different affordable and practical GPR‐based systems are used to validate a number of promising developments in signal processing techniques for target detection and identification. The proposed approaches have been validated with success in laboratory and outdoor conditions and for different scenarios, including antipersonnel, low‐metal content landmines, improvised explosive devices and real mine‐affected soils

Nondestructive evaluation of fiber reinforced polymer bridge decks using ground penetrating radar and infrared thermography

Recent studies have focused on the development of Fiber Reinforcement Polymer (FRP) as an alternative construction material for highway bridge decks.;The goal of this study was to explore the viability of nondestructive testing of FRP bridge decks using infrared thermography (IRT) and ground penetrating radar (GPR).;All tests were conducted on a 6\u27 x 3\u27 (1828.8mm x 914.4mm) low profile (4\u27\u27 or 101.6mm deep) FRP bridge deck and a 3\u27 x 2\u27 (914.4mm x 609.6mm) low profile FRP bridge deck specimen with embedded delaminations. Replaceable wearing surface modules with air-voids of varying sizes were used to simulate air-filled debonds between the wearing surface and the FRP bridge deck. To simulate the water-filled debonds, custom made water-pouches were placed in the air-voids.;Solar radiation, commercially available heater, and heating blankets were utilized as active heat sources in the IRT tests. The effectiveness of each heat source in subsurface detection of defects was examined.;A simple finite element model was created to study the heat transfer phenomena between the FRP bridge deck with wearing surface and the surroundings. The FE model enabled a theoretical study of the effect of subsurface defect thickness on the surface temperature profile. Results from the model were also compared to the experimental results obtained through the IRT tests.;A 1.5GHz ground-coupled antenna and a 2.0GHz air-coupled antenna were utilized in the GPR tests for this study. They were used in an attempt to identify both air-filled and water-filled debonds and delaminations. The effectiveness of each antenna in detecting subsurface defects was carefully examined.;The results of this study have shown that a combination of GPR and IRT techniques can lead to an effective nondestructive testing system for detecting subsurface defects in FRP Bridge Decks

Time-Frequency Analysis of Air-coupled GPR Data for Identification of Delamination between Pavement Layers

随着国家对交通基础设施的投入加大，全国高速公路的里程数日益增加，随之而来的道路工程问题也日益扩大，造成严重的社会影响和经济损失。探地雷达作为一种高性能的无损检测工具，不仅在工程勘探结果上直观准确，而且操作简便高效，在公路病害无损检测中已经得到广泛应用。然而，受限于探地雷达的工作带宽，在一些数值上需要精确测量的工程问题方面，探地雷达的分辨率仍然无法满足要求。 本文主要关注高速公路沥青面层与混凝土基层之间的剥离问题，利用时频分析工具对不同厚度薄层的雷达反射复合波频谱特性进行研究，从而提供一种道路层间剥离病害情况评估的参考依据。首先建立起沥青道路结构中间隙薄层的数值模型，利用分层介质格林函数（DG...With the mileage of the highway increasing, numbers of highway engineering issues arise, which causes serious damage to the social economy. Ground Penetrating Radar (GPR) is one kind of high performance non-destructive testing (NDT) technology. With its precise and efficient performance, GPR is comprehensively used in pavement inspection. However, limited by the bandwidth, the range resolution of ...学位：工程硕士院系专业：物理科学与技术学院_工程硕士(电子与通信工程)学号：3432014115280

Radar Technology

In this book “Radar Technology”, the chapters are divided into four main topic areas: Topic area 1: “Radar Systems” consists of chapters which treat whole radar systems, environment and target functional chain. Topic area 2: “Radar Applications” shows various applications of radar systems, including meteorological radars, ground penetrating radars and glaciology. Topic area 3: “Radar Functional Chain and Signal Processing” describes several aspects of the radar signal processing. From parameter extraction, target detection over tracking and classification technologies. Topic area 4: “Radar Subsystems and Components” consists of design technology of radar subsystem components like antenna design or waveform design

Realistic FDTD GPR antenna models optimized using a novel linear/nonlinear Full-Waveform Inversion

Finite-Difference Time-Domain (FDTD) modelling of Ground Penetrating Radar (GPR) is becoming regularly used in model-based interpretation methods like full waveform inversion (FWI), and machine learning schemes using synthetic training data. Oversimplifications in such forward models can compromise the accuracy and realism with which real GPR responses can be simulated, and this degrades the overall performance of the aforementioned interpretation techniques. Therefore, a forward model must be able to accurately simulate every part of the GPR problem that can affect the resulting scattered field. A key element is the antenna system and excitation waveform, so the model must contain a complete description of the antenna including the excitation source and waveform, the geometry, and the dielectric properties of materials in the antenna. The challenge is that some of these parameters are not known or easily measured, especially for commercial GPR antennas that are used in practice. We present a novel hybrid linear/non-linear FWI approach which can be used, with only knowledge of the basic antenna geometry, to simultaneously optimise the dielectric properties and excitation waveform of the antenna, and minimise the error between real and synthetic data. The accuracy and stability of our proposed methodology is demonstrated by successfully modelling a Geophysical Survey Systems (GSSI) Inc. 1.5~GHz commercial antenna. Our framework allows accurate models of GPR antennas to be developed without requiring detailed knowledge of every component in the antenna. This is significant because it allows commercial GPR antennas, regularly used in GPR surveys, to be more readily simulated

Enhancements of a three dimensional target model for deep ground penetrating radar systems

Both commercial and military industries incorporate the use of Ground Penetrating Radar (GPR). In the case of the military, a stationary object, such as a bunker or tunnel, can be detected. Even high-resolution, three-dimensional (3D) and twodimensional (2D) imagery of energy reflected by the target and its surrounding environment can be produced. This is accomplished using multiple scene perspectives inherent in advanced Synthetic Aperture Radar (SAR) techniques. Although underground target detection can be successful, the return data, usually suffers a significant degree of signal degradation due to the ground medium and target composition. A valid theoretical target model must account for adverse affects such as specular and diffuse reflections, dispersion and attenuation in order to provide an accurate representation of the simulated GPR scenario. It is the aim of this thesis to demonstrate the benefits of a high fidelity GPR target model. Demonstrated in the model is the ability to record estimative return power as a function of multiple variables including frequency, target depth, target composition, ground medium, complex antenna patterns, and transmitted power. Using ray-tracing, a bidirectional reflectance distribution function (BRDF), and 3D geometric analysis, the specular and diffuse reflective and refractive sub-surface energy interactions known to take place for a spatially complex target are simulated. Results culminate in the comparison of 3D and 2D imagery generated using this target model with imagery generated using previous models

NASA Tech Briefs, July 2013

Dielectrophoresis-Based Particle Sensor Using Nanoelectrode Arrays; Multi-Dimensional Damage Detection for Surfaces and Structures; ULTRA: Underwater Localization for Transit and Reconnaissance Autonomy; Autonomous Cryogenic Leak Detector for Improving Launch Site Operations; Submillimeter Planetary Atmospheric Chemistry Exploration Sounder; Method for Reduction of Silver Biocide Plating on Metal Surfaces; Silicon Micromachined Microlens Array for THz Antennas; Forward-Looking IED Detector Ground Penetrating Radar; Fully Printed, Flexible, Phased Array Antenna for Lunar Surface Communication, Battery Charge Equalizer with Transformer Array; An Efficient, Highly Flexible Multi-Channel Digital Downconverter Architecture; Dimmable Electronic Ballast for a Gas Discharge Lamp; Conductive Carbon Nanotube Inks for Use with Desktop Inkjet Printing Technology; Enhanced Schapery Theory Software Development for Modeling Failure of Fiber-Reinforced Laminates; High-Performance, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants; Carbon Nanotube Microarrays Grown on Nanoflake Substrates; Differential Muon Tomography to Continuously Monitor Changes in the Composition of Subsurface Fluids; Microgravity Drill and Anchor System; 20 Granular Media-Based Tunable Passive Vibration Suppressor; 21 Miga Aero Actuator and 2D Machined Mechanical Binary Latch; Micro-XRF for In Situ Geological Exploration of Other Planets; Hydrogen-Enhanced Lunar Oxygen Extraction and Storage Using Only Solar Power; Uplift of Ionospheric Oxygen Ions During Extreme Magnetic Storms; Miniaturized, High-Speed, Modulated X-Ray Source; Hollow-Fiber Spacesuit Water Membrane Evaporator 25 High-Power Single-Mode 2.65-micrometers InGaAsSb/AlInGaAsSb Diode Lasers; Optical Device for Converting a Laser Beam Into Two Co-aligned but Oppositely Directed Beams; A Hybrid Fiber/Solid-State Regenerative Amplifier with Tunable Pulse Widths for Satellite Laser Ranging; X-Ray Diffractive Optics; SynGenics Optimization System (SynOptSys); 29 CFD Script for Rapid TPS Damage Assessment; radEq Add-On Module for CFD Solver Loci-CHEM; Science Opportunity Analyzer (SOA) Version 8; 30 Autonomous Byte Stream Randomizer; Distributed Engine Control Empirical/Analytical Verification Tools; Dynamic Server-Based KML Code Generator Method for Level-of-Detail Traversal of Geospatial Data; Automated Planning of Science Products Based on Nadir Overflights and Alerts for Onboard and Ground Processing; Linked Autonomous Interplanetary Satellite Orbit Navigation; Risk-Constrained Dynamic Programming for Optimal Mars Entry, Descent, and Landing; Scheduling Operations for Massive Heterogeneous Clusters; Deepak Condenser Model (DeCoM); Flight Software Math Library; Recirculating 1-K-Pot for Pulse-Tube Cryostats; 35 Method for Processing Lunar Regolith Using Microwaves; Wells for In Situ Extraction of Volatiles from Regolith (WIEVR); and Estimating the Backup Reaction Wheel Orientation Using Reaction Wheel Spin Rates Flight Telemetry from a Spacecraft