A5040166094- Soil Moisture and Remote Sensing
- Cryospheric studies and observations
- Climate change and permafrost
- Terahertz technology and applications
- Microwave Imaging and Scattering Analysis
- Synthetic Aperture Radar (SAR) Applications and Techniques
- Geophysical Methods and Applications
- Microwave and Dielectric Measurement Techniques
- Millimeter-Wave Propagation and Modeling
- Arctic and Antarctic ice dynamics
- Precipitation Measurement and Analysis
- Electromagnetic Compatibility and Measurements
- Remote Sensing and LiDAR Applications
- Transportation Systems and Safety
- Photonic Crystals and Applications
- Advanced Optical Sensing Technologies
- Astronomical Observations and Instrumentation
- Superconducting and THz Device Technology
- Face recognition and analysis
- Advanced SAR Imaging Techniques
- Radiation Detection and Scintillator Technologies
- Digital Media Forensic Detection
- Archaeology and Natural History
- User Authentication and Security Systems
- Gamma-ray bursts and supernovae
Stanford University
2021-2025
Northeastern University
2017-2021
Abstract Because of the remote nature permafrost, it is difficult to collect data over large geographic regions using ground surveys. Remote sensing enables us study permafrost at high resolution and areas. The Arctic‐Boreal Vulnerability Experiment's Permafrost Dynamics Observatory (PDO) contains about subsidence, active layer thickness (ALT), soil water content, table depth, derived from airborne radar measurements 66 image swaths in 2017. With nearly 58,000,000 pixels available for...
Abstract The extent of wildfires in tundra ecosystems has dramatically increased since the turn 21st century due to climate change and resulting amplified Arctic warming. We simultaneously studied recovery vegetation, subsurface soil moisture, active layer thickness post-fire permafrost-underlain uplands Yukon-Kuskokwim Delta southwestern Alaska understand interaction between these factors their potential implications. used a space-for-time substitution methodology with 2017 Landsat 8...
Abstract Seasonal subsidence induced by ground ice melt can be measured interferometric synthetic aperture radar (InSAR) techniques to infer active layer thickness (ALT) in permafrost regions. The magnitude of depends on both how deep the soil thawed and much ice/water content existed soil. To provide later, P‐band polarimetric (PolSAR) backscatter is used due its sensitivity subsurface moisture freeze/thaw conditions. In this study, which second a two‐part series Permafrost Dynamics...
Soil moisture can vary spatially at the scale of agricultural fields (~ 10 − 100 m), which is generally too fine to resolve using passive radiometric methods. Active radar provides an opportunity for finer resolution measurements; in particular, interferometric synthetic aperture (InSAR) closure phase parameter sensitive changing soil moisture. We have developed a model showing that systematic non-zero result from scattering objects different depths medium time-varying dielectric, such as...
Abstract. Permafrost-affected ecosystems of the Arctic–boreal zone in northwestern North America are undergoing profound transformation due to rapid climate change. NASA's Arctic Boreal Vulnerability Experiment (ABoVE) is investigating characteristics that make these vulnerable or resilient this ABoVE employs airborne synthetic aperture radar (SAR) as a powerful tool characterize tundra, taiga, peatlands, and fens. Here, we present an annotated guide L-band P-band SAR data acquired during...
In permafrost regions, active layer thickness (ALT) observations measure the effects of climate change and predict hydrologic elemental cycling. Often, ALT is measured through direct ground-based measurements. Recently, synthetic aperture radar (SAR) measurements from airborne platforms have emerged as a method for observing seasonal thaw subsidence, soil moisture, in regions. This study validates SAR-derived estimates three regions Alaska, USA using calibrated ground penetrating (GPR)...
Fast detection of hazardous objects in millimeter-wave personnel screening can increase the operating efficiency secure environments. In airports, accurate automatic and classification body-worn reduce number pat-downs while keeping transportation environment safe secure. Since many benign objects, such as paper leather, are lossy materials, being able to characterize them set aside from secondary checks will significantly process time. this article, we introduce an effective...
The efficiency and effectiveness of airport security can be improved through fast high-fidelity detection concealed threat objects. If detected objects accurately characterized, the number false alarms will reduced, whereas terrorist threats more quickly noticed apprehended. This article aims to characterize physical properties weak dielectric (such as explosive threats) covering a conductive plane human body) using single-frequency millimeter-wave (mm-wave) radar system with Fresnel...
We propose a fast and accurate method of finding the thickness dielectric permittivity weak objects using focused continuous-wave radar security scanning system, to characterize that may be explosive threats. Building on previously developed ray-based Virtual Source model for sensing scattering from slabs, this work presents an inversion algorithm two observable CW millimeter wave probe parameters by considering expected small variations slab over its surface. The determination works...
Abstract. Permafrost-affected ecosystems of the Arctic-boreal zone in northwestern North America are undergoing profound transformation as a result rapid climate change. NASA’s Arctic Boreal Vulnerability Experiment (ABoVE) is investigating characteristics that make these vulnerable or resilient to this ABoVE employs airborne synthetic aperture radar (SAR) powerful tool characterize tundra, taiga, peatlands, and fens. Here, we present an annotated guide L-band P-band SAR data acquired during...
InSAR (interferometric synthetic aperture radar) phase closure, the net from linking three multilooked interferograms formed acquisitions, has been linked to soil moisture [1]. Here, we show one possible way predict closure. Our data reduction approach includes an integration of closure over time and subtraction a random walk component relate differential values level. We find that for large test region Oklahoma, integrated using Sentinel-1 tracks observed in field. In other cases, match is...
We present a novel non-iterative model based on ray analysis to characterize non-metallic, weak dielectric objects (like threat objects) the surface of highly conducting background human body) using focused continuous millimeter-wave sensor. For simple constant thickness slab ground plane, there are five primary scattering phenomena that must be considered.
Efficient characterization of concealed person-worn objects enhances the security air travel and reduces inspection time.Mm-wave nearfield radar can detect metallic such as guns or knives, well water-based materials that might be associated with peroxide threats.However, it cannot discriminate these potential threats from benign to decrease nuisance alarm rate.Moreover, distinguishing in presence human skin is even more challenging.The authors have previously developed a method using mm-wave...
<p>Soil moisture can vary spatially at the scale of agricultural fields (~10 -100 m), which is generally too fine to resolve using passive radiometric methods. Active radar provides an opportunity for finer resolution measurements; in particular, interferometric synthetic aperture (InSAR) closure phase parameter sensitive changing soil moisture. We have developed a model showing that systematic non-zero result from scattering objects different depths medium time-varying dielectric,...
This paper details a model for weak dielectric object on the human body with small gap between and body, as detected by CW millimeter-wave security scanning system. is refinement of Virtual Source Model, focusing possibility that not directly against skin. Seven primary scattering phenomena are considered in this model, more than model; later have negligible amplitude. Even can cause significant difference return.
The Permafrost Dynamics Observatory (PDO) combines L-band interferometric synthetic aperture radar (InSAR) and P-band polarimetric (PolSAR) to simultaneously estimate the seasonal thaw depth soil moisture profile of active layer in permafrost regions. InSAR can measure subsidence due thawing PolSAR backscatter is sensitive subsurface moisture. A joint retrieval scheme developed as both are essential accurate thickness (ALT) estimation. PDO has been applied airborne L- SAR data acquired over...
This paper proposes a method for determining permittivity and thickness of body-borne objects automatically by processing wideband radar images. The algorithm can be used to find the explosive threats rule out benign objects. Having reconstructed millimeter wave image body with an anomaly attached it, we extract nominal contour, which shows surface in absence object, then subtract ideal response from define amount displacement observed is caused signal retardation due presence weak...
<p>Soil moisture can vary spatially at the scale of agricultural fields (~10 -100 m), which is generally too fine to resolve using passive radiometric methods. Active radar provides an opportunity for finer resolution measurements; in particular, interferometric synthetic aperture (InSAR) closure phase parameter sensitive changing soil moisture. We have developed a model showing that systematic non-zero result from scattering objects different depths medium time-varying dielectric,...
This paper compiles measured complex dielectric constants of benign and hazardous materials used for developing algorithms personnel scanners at airports 30 GHz. The are grouped into broad classifications potential threat by mapping the to constant plane.
Fast and accurate characterization of concealed threats benign objects is great importance for increasing the efficiency mm-wave imaging radar personnel screening systems in airports. Correctly classifying low-loss lossless materials essential detecting threats. Previous work developed a real-time, fully automatic algorithm characterizing lossy vs. materials. This paper extends image-processing-based method to distinguish media, such as materials, that include explosives. The verified...
We develop a model for dielectric-coated perfectly conducting cylinder, as imaged by wideband millimeter-wave radar security scanning system. This images concealed dielectric objects, when attached to realistically curved body parts, including the human arm or leg. The is compared that of planar slab on plane, and it proven be nearly identical dielectrics with thickness less than half cylinder radius.