Experimental Study of White Heat Line Formation in Burned Bone Using Fourier Transform Infrared Spectroscopy

In anthropological analysis of burned bone, the presence of a white heat line (WHL) aids in determining a bone’s physical condition prior to burning, distinguishing between those burned fleshed or wet versus dry, making this thermal signature an important source of information regarding the relative timing of burning. While the relationship between WHLs and a bone’s physical condition has been studied, there is a lack of research concerning WHL chemical composition. The present study assessed the composition of WHLs that form on burned bone using Fourier Transform Infrared Spectroscopy (FTIR), including the effects of soft tissue and retention of bone’s organic material on a WHL’s development and appearance. Experimental remains consisted of isolated bones from pig (Sus scrofa), sheep (Ovis aries), white-tailed deer (Odocoileus virginianus), and elk (Cervus elaphus) in five physical conditions: fleshed, defleshed/very wet, partially wet, dry, and dry/soaked. Chemical composition was analyzed using spectral peak heights of the carbonate (CO3) ν3 (1415 cm-1), phosphate (PO4) ν3 (1035 cm-1), and amide I (1660 cm-1) vibrational bands. WHLs formed on 8 of 16 bones burned fleshed (50%) compared to 8 of 27 defleshed/very wet (29.6%). The partially wet, dry, and dry/soaked sample groups did not develop a WHL. Results indicate WHLs that formed on fleshed bone contained an increased amount of CO3, PO4, and amide I versus unburned controls. In contrast, WHLs that formed on defleshed/very wet bone contained decreased amounts. Additional research is needed to explore the exact mechanisms causing the formation of WHLs and their physical appearance.

Using Graphene-Based Composite Materials to Boost Anti-Corrosion and Infrared-Stealth Performance of Epoxy Coatings

Corrosion prevention and infrared (IR) stealth are conflicting goals. While graphene nanosheets (GN) provide an excellent physical barrier against corrosive agent diffusion, thus lowering the permeability of anti-corrosion coatings, they have the side-effect of decreasing IR stealth. In this work, the anti-corrosion properties of 100-μm-thick composite epoxy coatings with various concentrations (0.01–1 wt.%) of GN fillers thermally reduced at different temperatures (300 °C, 700 °C, 1100 °C) are first compared. The performance was characterized by potentiodynamic polarization scanning, electrochemical impedance spectroscopy, water contact angle and salt spray tests. The corrosion resistance for coatings was found to be optimum at a very low filler concentration (0.05 wt.%). The corrosion current density was 4.57 × 10−11 A/cm2 for GN reduced at 1100 °C, showing no degradation after 500 h of salt-spray testing: a significant improvement over the anti-corrosion behavior of epoxy coatings. Further, to suppress the high IR thermal signature of GN and epoxy, Al was added to the optimized composite at different concentrations. The increased IR emissivity due to GN was not only eliminated but was in fact reduced relative to the pure epoxy. These optimized coatings of Al-GN-epoxy not only exhibited greatly reduced IR emissivity but also showed no sign of corrosion after 500 h of salt spray test.

SMART Protocol Using Polarized Infrared Cameras

Tier II/III SMART protocol for dispersant use requires placing fluorometers in the water and towing them under a slick by boat. To protect the health of SMART teams, boats typically remain at least 2 miles away from slicks during aerial dispersant treatment. After the spray completes, the SMART boats transit into oil slicks. The time between completion of spray and initiation of SMART monitoring can be > 30 minutes. In 30 minutes, dispersed oil plumes will significantly dilute making them difficult to detect based on fluorescence. Further, we identified a separate issue. That is, oil fluoresces primarily because of the aromatic constituents in the oil and many of the aromatics in oil are at least somewhat volatile and water soluble. Modeling found that these aromatics leach from the oil prior to the application of dispersant. So, even if fluorometers were immediately underneath dispersing oils slicks, the loss of aromatics from the oil challenges SMART. The combination of aromatic leaching and rapid plume dilution limits the ability of the Tier II/III SMART protocol to identify fluorescence signals above the recommended five times background. This means that effectively dispersed oil slicks might not be accurately characterized. What is needed is a monitoring technique that can be applied rapidly and targets some other characteristic of the oil. Polarized infrared (IR) cameras can measure both the thermal differences between slicks and water and the difference in emissivity when IR energy is emitted by sheens / slicks relative to water. These cameras can be easily flown on dispersant spray/support planes. They can be used to image oil slicks before, during, and after dispersant spray operations. Effectively dispersed oil slicks will have a significant change in their thermal signature and IR emissivity as the oil transfers from the water surface into the water column. Polarized infrared cameras can be an effective tool for monitoring dispersant operations. They can be deployed continually during slick dispersion providing a longitudinal and synoptic record of the dispersion process. In this paper, we describe modeling to estimate the water-column concentrations of aromatic hydrocarbons (both mono and polycyclic) from plumes after applying dispersants to an oil slick. In addition, we describe testing of a polarized IR camera at the OHMSETT tank during dispersant testing. We use the modeling to identify the need for modifying SMART and the OHMSETT testing to show that polarized IR cameras can meet this need.

Detecting Small Size and Minimal Thermal Signature Targets in Infrared Imagery Using Biologically Inspired Vision

Thermal infrared imaging provides an effective sensing modality for detecting small moving objects at long range. Typical challenges that limit the efficiency and robustness of the detection performance include sensor noise, minimal target contrast and cluttered backgrounds. These issues become more challenging when the targets are of small physical size and present minimal thermal signatures. In this paper, we experimentally show that a four-stage biologically inspired vision (BIV) model of the flying insect visual system have an excellent ability to overcome these challenges simultaneously. The early two stages of the model suppress spatio-temporal clutter and enhance spatial target contrast while compressing the signal in a computationally manageable bandwidth. The later two stages provide target motion enhancement and sub-pixel motion detection capabilities. To show the superiority of the BIV target detector over existing traditional detection methods, we perform extensive experiments and performance comparisons using high bit-depth, real-world infrared image sequences of small size and minimal thermal signature targets at long ranges. Our results show that the BIV target detector significantly outperformed 10 conventional spatial-only and spatiotemporal methods for infrared small target detection. The BIV target detector resulted in over 25 dB improvement in the median signal-to-clutter-ratio over the raw input and achieved 43% better detection rate than the best performing existing method.