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Northwest Electromagnetics & Acoustics Research Laboratory Dr. Lisa Zurk, Director http://nearlab.ece.pdx.edu/ The NEAR-Lab focus is on the modeling and analysis of electromagnetic and acoustic wave phenomenon for development of advanced signal processing techniques. The understanding of wave scattering provides a basis to devise and evaluate advanced signal processing algorithms for applications such as radar, sonar, and biomedical imaging. NEAR-Lab Electromagnetics Research Projects: • Scattering models for Synthetic Aperture Radar • Correlation processing for detection of land mines • Rough surface scattering from target multipath • Terahertz imaging for explosive detection and biomedical imaging Comparison of NEAR-Lab rough surface scattering codes Comparison of Synthetic Aperture Radar (SAR) image with optical image (SAR image is from the MIT Lincoln Multi-mission ISR Testbed, LiMIT) Radar multipath modeling (collaboration with MIT) Direct Target-Ground eik ( 2 r r ) r (r r ) e ik ( 2 r ) r2 Ground-Target ik ( 2 r r ) e r (r r ) Ground-TargetGround ik 2 ( r r ) e (r r ) 2 Scattering models for correlation processing applied to radar detection of land mines; exploits structure of signature from buried object (collaboration with Dr Timchenko, Inst. RadioPhys., Ukraine) Research Spotlight: Terahertz Imaging Until recently, little was known about properties of the terahertz region (terahertz = 1012, between microwave and visible) of the electromagnetic spectrum, earning it the title of the “THz Gap”. However, recent advances in ultrafast optics have provided the means to generate and measure THz signals, and this has opened the possibility of THz sensing with a multitude of potential applications. Two of the most promising – detection of explosive materials and biomedical imaging – are being actively explored in the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab). The research is supported by grants from the Office of Naval Research (ONR) and the National Science Foundation (NSF), and is in collaboration with the Applied Physics Laboratory at the University of Washington. Selected NEAR-Lab Electromagnetics Publications & Presentations: HMX explosive granular structure (image from LLNL UCRL-PRES150298) Coupled grain scattering: random media models (“Swiss cheese” model) Data and model comparison showing experimental scattering by Large Grain PE (LGPE) versus Small Grain PE (SGPE) explained well with dense media theory, Quasi-crystalline approximation (QCA) (Data provided by University of Maryland, Baltimore County) Reference SGPE (data) LGPE (data) SGPE (QCA) LGPE (QCA) 2 Relative Spectral Level 10 1 10 0 10 0 2 4 6 Frequency (THz) 8 L.M. Zurk, “Scattering in Random Media Applied to Terahertz Time Domain Spectroscopy”, (invited presentation), Progress in Electromagnetic Research Sym. (PIERS), Beijing, China, Mar. 2007 L.M. Zurk, B. Orlowski, G. Sundberg, D.P Winebrenner, E.I Thorsos, A. Chen, “Electromagnetic Scattering Calculations for Terahertz Sensing”, Proc. of SPIE, San Jose, CA, Jan. 2007 L.M. Zurk1, B. Jouni, F. Farahbakhshian, D.P. Winebrenner, E.I. Thorsos, A. Chen, M. R. Leahy-Hoppa, L.M. Hayden, “Scattering Calculations for Evaluation of Terahertz Detection of Explosive Material”, Seventh International Symposium on Technology and the Mine Problem (MINWARA), Monterey, CA, May 2006 R. Toengi, “Airborne Synthetic Aperture Radar (SAR) Terrain-Based Processing”, MS Thesis L. M. Zurk, S. Matzner, F. Farahbakhshian, R. Toengi, "Electromagenetic Modelling for Interpretation of Airborne SAR Imagery," PIERS, Cambridge, MA, March 2006. L. M. Zurk, B. Jouni, F. Farahbakhshian, "Calculation of Scattering from Polyethylene Particles Compared with Terahertz Measurements," PIERS, Cambridge, MA, March 2006. S. Matzner, L. M. Zurk, A. I. Timchenko, "Radar Detection of Subsurface Objects Using Correlation Imaging," PIERS, Cambridge, MA, March 2006. A. I. Timchenko, L. M. Zurk, "Signal Processing Methods for Detection of Subsurface Objects by Ultra-wideband SAR," IEEE GRS, Korea, July 2005. 10 NEAR-Lab Research involves numerical modeling, development of theory, and participation in large-scale collaborative experimentation efforts Northwest Electromagnetics & Acoustics Research Laboratory Dr. Lisa Zurk, Director http://nearlab.ece.pdx.edu/ The NEAR-Lab focus is on the modeling and analysis of electromagnetic and acoustic wave phenomenon for development of advanced signal processing techniques. The understanding of wave scattering provides a basis to devise and evaluate advanced signal processing algorithms for applications such as radar, sonar, and biomedical imaging. Fish aggregation & spawning • Physics-based processing for active sonar networks • Acoustic propagation into ocean bottom sediments • Sonar mapping of coral reefs and fish aggregation • Array processing of passive sonar systems Acoustic source Target Time/frequency spectra Bottom reverberation Echogram Data from Malta Plateau (Italy) showing observed striation patterns, and excellent agreement with NEAR-Lab model predictions. Spectrogram(Data) -10 Spectrogram(Simulation) -5 20 20 40 40 60 Time(min) Active sonar geometry, with normal mode propagation effects for acoustic energy Bathmetry map of Half Moon Caye, Belize, from sonar echo-sounding data (collaboration with the Nature Conservancy) -15 80 100 120 -10 40 60 80 80 -15 100 -20 Range vs time 20 60 dB Acoustics Research Projects: NEAR-Lab 100 120 120 -20 140 140 140 160 160 160 450 500 550 Frequency(Hz) -25 450 500 550 Frequency(Hz) -25 16 18 20 22 24 26 Range(km) Research Spotlight: Ocean Bottom Profiling There are a number of applications – such as marine habitat monitoring, mine detection, and Navy sonar operation - in which the profile of the ocean bottom is required. However, this information is generally difficult to obtain and prone to inaccuracy. One promising approach is to use a broadband sonar pulse (for example, a chirp signal) that can penetrate into the bottom, and then measure the timefrequency content of the reflected energy. Theoretically, this signal contains information on the acoustic properties of all the layers, but interpretation of this information is difficult due to scattering from ocean layers and buried inhomogeneities (for example, shells and rocks). Research in the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab) is helping address this by developing acoustic scattering models, and validating these models with data from the Navy’s Shallow Water 2006 experiment. This is in collaboration with Applied Physics Laboratory, University of Washington and the Naval Research Laboratory (NRL). Incident acoustic wave Specular reflection Rough surface Acoustic scattering can occur due to multiple phenomenon: specular reflection, rough surface scattering, volume scattering, and layer scattering. c0 , 0 c1 , 1 Volume scattering Layer scattering Chirp sonar experiment c2 , 2 Bottom layer 1 Bottom layer 2 Bottom layer n c3 , 3 The Navy-sponsored Shallow Water 2006 (SW06) experiment took place in August on the New Jersey shelf. PSU student Jorge Quijano participated in the experiment on the Research Vessel Knorr (owned by MIT Woods Hole) and in collaboration with APL/UW and NRL. Jorge was responsible for taking Conductivity- Temperature-Depth (CTD) measurements during the experiment, and will be using the chirp sonar data as part of his PhD dissertation. 0 Jorge on RV Knorr 5 Depth(m) 10 15 20 25 30 Chirp sonar from SW06 (courtesy of NRL) 1000 2000 3000 Ping number 4000 5000 Selected NEAR-Lab Acoustics Publications & Presentations: L.M. Zurk, J. Quijano, M. Velankar, D. Rouseff, “Bistatic invariance for active sonar systems”, Acoustical Society of America (ASA), Honolulu, HI, Jan 2007 L.M. Zurk, J. Lotz, T. Ellis, J. McNames, J. Ecochard, “Sonar mapping for coral reef conservation”, ASA, HI, 2007 J. Quijano, L.M. Zurk, A. Turgut, D.J. Tang, “Ocean bottom scattering: characterization with chirp sonar”, ASA, HI, 2007 L. M. Zurk, D. Rouseff, G. Greenwood, "Bistatic Invariance Principle for Active Sonar Geometries," European Conference on Underwater Acoustics (ECUA), Carvoviero, Portugal, June 2006 J. Quijano, Use of the Invariance Principle for Target Tracking in Active Sonar Geometries”, MS Thesis J. Quijano, L.M. Zurk, “Use of the invariance principle for target tracking in active sonar geometries”, IEEE Oceans, Providence, RI, 2006 L. M. Zurk, B. H. Tracey, "Depth-shifting of guide sources," Oct 2005, JASA, N118 (4). L. M. Zurk, "Guide Source Depth and Range Translation for Robert MFP," ASA, Minneapolis, October 2005 M. R. Velankar, L. M. Zurk, "Mode-Based Adaptive processing in uncertain environments," ASA, Minneapolis, October 2005 L. M. Zurk, M. R. Velankar, "Passive Sonar Array Sub-space Processing based on Modal Decomposition," IEEE Oceans, Washington DC, October 2005. L. M. Zurk, "Performance of Mode-based Processing in Presence of Environmental Uncertainty," ASA, Vancouver, Canada, May 2005. NEAR-Lab Research involves numerical modeling, development of theory, and participation in large-scale collaborative experimentation efforts