Processing and Probability Analysis of Pulsed Terahertz NDE of Corrosion under Shuttle Tile Data
This paper examines data processing and probability analysis of pulsed terahertz NDE scans of corrosion defects under a Shuttle tile. Pulsed terahertz data collected from an aluminum plate with fabricated corrosion defects and covered with a Shuttle tile is presented. The corrosion defects imaged were fabricated by electrochemically etching areas of various diameter and depth in the plate. In this work, the aluminum plate echo signal is located in the terahertz time-of-flight data and a threshold is applied to produce a binary image of sample features. Feature location and area are examined and identified as corrosion through comparison with the known defect layout. The results are tabulated with hit, miss, or false call information for a probability of detection analysis that is used to identify an optimal processing threshold.
Ultrasonic and advanced methods for nondestructive testing and material characterization
Ultrasonic Methods: Fundamentals Models and Measurements for Ultrasonic Nondestructive Evaluation Systems (L W Schmerr Jr.) Integrated and Flexible High Temperature Piezoelectric Ultrasonic Transducers (C-K Jen & M Kobayashi) Real-Time and In-Line Ultrasonic Diagnostics of Polymer Processes (C-K Jen et al.) Guided Wave Based Nondestructive Testing: A Reference-Free Pattern Recognition Approach (H Sohn et al.) Acoustic Nonlinear Imaging and Its Application in Tissue Characterization (D Zhang & X-F Gong) Advanced (Other) Methods: Electromagnetic NDE Techniques for Materials Characterization (B P C Rao et al.) Terahertz NDE for Aerospace Applications (R F Anastasi et al.) Large Area Time Domain Terahertz (T-Ray) Imaging Non-Destructive Evaluation for Security and Aerospace (D Zimdars et al.) Active Infrared Thermography Techniques for the Nondestructive Testing of Materials (C Ibarra-Castanedo et al.) Quantitative Evaluation of Emerging Infrared Thermography Technologies for Aerospace Applications (J DiMambro) Signal and Image Processing in NDE: Computational Intelligence Methodologies for Non-Destructive Testing/Evaluation Applications (M Cacciola et al.) Split Spectrum Processing and Automatic Flaw Detection (K D Donohue) Homomorphic Deconvolution of Ultrasonic Images (R Jirik & T Taxt) and other papers.
Chemosymbiotic bivalves and stable carbon isotopes indicate hydrocarbon seepage at four unusual Cenozoic fossil localities
Four unusual Cenozoic fossil localities are identified here as ancient hydrocarbon seep sites using palaeontological, petrological, and stable carbon isotope data. Late Eocene carbonate-cemented sandstone bodies in the Wagonwheel Mountains in California were previously suspected to represent ancient hydrocarbon seep sites, but the relatively high δ13Ccarbonate values (−12.2 to −5.0‰) suggest oil rather than methane seepage. The Oligocene fauna of the Elmira asphalt mine, Cuba, was previously interpreted as a mix of freshwater and marine taxa, but all species are here identified as belonging to marine groups, including the bivalve families Lucinidae and Vesicomyidae, whose extant members live largely in symbiosis with chemoautotrophic endosymbionts. A carbonate concretion from this site showed δ13Ccarbonate values as low as −32.2‰, which most likely indicates methane seepage. A previously unpublished Oligocene fossil locality in Atlantico, northern Colombia, is dominated by large solemyid, mytilid, lucinid, and vesicomyid bivalves, which most likely lived with chemotrophic endosymbionts. Seepage of biogenic methane without a significant contribution of thermogenic methane is indicated by δ13Ccarbonate values as low as −51.3‰. We confirm that the Pleurophopsis-dominated sites of the Heath Shale and Lomitos Chert in northern Peru are ancient seep sites, although the previous identification of Pleurophopsis peruviana as a vesicomyid is doubtful.