Pseudorabies and the Move Toward Eradication

Pseudorabies (PR) is receiving more attention today than ever before. Why is this? Historically, PR can be traced back to the mid 1800\u27s in the United States. Although sporadic outbreaks were reported prior to 1975, it was not until the late 70\u27s and 80\u27s that the importance of PR was appreciated. This can possibly be explained by an increasing incidence of clinical disease outbreaks, and economic losses associated with those outbreaks. Three reasons have been suggested for the increase in recent outbreaks!: (1) there has been a change in swine management towards intensification of producand confinement (2) there has been a successful eradication of Hog Cholera, and since it and PR can have similar clinical signs, more PR is being recognized (3) there has been an increase in awareness of PR as a disease entity

Trans-Laminar-Reinforced (TLR) Composites

A Trans-Laminar-Reinforced (TLR) composite is defined as composite laminate with up to five percent volume of fibrous reinforcement oriented in a 'trans-laminar' fashion in the through-thickness direction. The TLR can be continuous threads as in 'stitched laminates', or it can be discontinuous rods or pins as in 'Z-Fiber(TM) materials. It has been repeatedly documented in the literature that adding TLR to an otherwise two dimensional laminate results in the following advantages: substantially improved compression-after-impact response; considerably increased fracture toughness in mode 1 (double cantilever beam) and mode 2 (end notch flexure); and severely restricted size and growth of impact damage and edge delamination. TLR has also been used to eliminate catastrophic stiffener disbonding in stiffened structures. TLR directly supports the 'Achilles heel' of laminated composites, that is delamination. As little as one percent volume of TLR significantly alters the mechanical response of laminates. The objective of this work was to characterize the effects of TLR on the in-plane and inter-laminar mechanical response of undamaged composite laminates. Detailed finite element models of 'unit cells', or representative volumes, were used to study the effects of adding TLR on the elastic constants; the in-plane strength; and the initiation of delamination. Parameters investigated included TLR material, TLR volume fraction, TLR diameter, TLR through-thickness angle, ply stacking sequence, and the microstructural features of pure resin regions and curved in-plane fibers. The work was limited to the linear response of undamaged material with at least one ply interface. An inter-laminar dominated problem of practical interest, a flanged skin in bending, was also modeled

Lamb Wave Tomography for Corrosion Mapping

As the world-wide civil aviation fleet continues to age, methods for accurately predicting the presence of structural flaws-such as hidden corrosion-that compromise airworthiness become increasingly necessary. Ultrasonic guided waves, Lamb waves, allow large sections of aircraft structures to be rapidly inspected. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical-waveguide physics. Our work focuses on using a variety of different tomographic reconstruction techniques to graphically represent the Lamb wave data in images that can be easily interpreted by technicians. Because the velocity of Lamb waves depends on thickness, we can convert the travel times of the fundamental Lamb modes into a thickness map of the inspection region. In this paper we show results for the identification of single or multiple back-surface corrosion areas in typical aluminum aircraft skin structures

Low-cost wave characterization modules for oil spill response

Marine oil spills can be remediated by mechanical skimmers in calm waters, but performance degrades with increased wave height. We have developed and demonstrated a system that quantifies local wave characteristics with an uncertainty of four inches of heave. Our system is intended for the measurement of wave characteristics during oil spill recovery. It conveys this information to coordinators and responders in real time via WiFi and remote reporting through a satellite network. This information will allow for enhanced situational awareness during an oil spill response, assisting stakeholders and optimizing mechanical skimming operations. Our wave characterization module (WCM) uses accelerometer outputs from a very small inertial measurement unit (IMU) to generate wave statistics and calculate wave characteristics. It is configured such that a WCM can either be attached to a skimmer float or incorporated into a microbuoy. Wave height and period are transmitted via WiFi and/or a satellite-enabled mesh-grid network to a cloud-hosted geographic information system (GIS). Here, we discuss the bare-bones sensors-plus-algorithm approach we developed by using spring-mass systems to approximate the wave height and period regime of interest. We then describe open water tests carried out using that development system both mounted to a weir skimmer mockup and packaged in a microbuoy. Finally, we present controlled tests in the wave tank at Ohmsett, the National Oil Spill Response Test Facility in New Jersey, with the WCMs communicating the wave characteristics via WiFi to tankside laptops and via satellite to the cloud-based GIS. Snapshot determinations of wave height calculated using the scalar magnitude of the three-axis accelerometer in the IMU were within four inches of the benchmark wave measurement system at Ohmsett. (C) 2018 Shanghai Jiaotong University. This is an open access article under the CC BY-NC-ND license

Ultrasonic Bacscatter from Embedded Cylinders

Advanced composite materials present unique challenges for nondestructive evaluation of their material properties and state of health or damage. Stitches and other through-the-thickness reinforcements are becoming much more common because of their ability to give substantially improved three-dimensional strength to finished components. They also allow textile preforms to hold their shapes before and during resin transfer molding, and can be important in automated tow-placement processes. Ultrasonic testing of advanced composites is desirable before, during and after consolidation and curing in order to monitor both the initial fabrication and the eventual inevitable structural degradation as the composite structure ages. Unfortunately, the very stitches that improve the properties of the composites interfere with the usual inspection methods. This difficulty can be overcome, however, if the interaction of the probing ultrasonic radiation with the through-the-thickness reinforcements can be understood and quantified. In this paper we present the results of our recent study which has considered theoretically and experimentally the scattering of elastic waves from embedded cylindrical elastic scatterers. In particular, we have derived an exact and analytic, closed-form solution for the oblique polar backscatter from these structures and then have compared our theoretical results with ultrasonic immersion tank experiments conducted on wires, fibers and tows embedded in polymeric materials

Acoustic Space is Affected by Anthropogenic Habitat Features: Implications for Avian Vocal Communication

Human-altered landscapes often include structural features, such as higher levels of impervious surface cover (ISC) and less vegetation, that are likely to affect the transmission of avian vocalizations. We investigated the relationships between human habitat modifications and signal transmission by measuring four acoustic parameters—persistence, reverberation, and signal-to-noise ratio (SNR) of broadcast tones, as well as absolute ambient noise level—in each of 39 avian breeding territories across an anthropogenic disturbance gradient. Using a geographic information system, we quantified the amounts of different habitat features (e.g., ISC, grass, trees) at each site; a principal component analysis was used to identify which of these habitat features commonly co-occurred (e.g., “habitat suites”). Finally, we used a model selection process to explore whether the habitat suites predicted the acoustic parameters. Tone persistence was higher and reverberation was lower in more open, grassy habitats than in areas with more vertical anthropogenic structures. In more human-modified sites, ambient noise levels were higher, leading to lower SNR. In habitats with low levels of human modification, we found that even small increases in the total amount of open—grassy area will quickly improve the acoustic space of singing birds. However, our results also indicated that there may be a critical level of human habitat modification above which the addition of “natural” areas does not benefit avian communication. Thus, we recommend that managers focus their efforts on preserving pre-existing “natural” habitat, rather than attempting to introduce it into areas that have already received significant human modification

3D Ultrasonic Wave Simulations for Structural Health Monitoring

Structural health monitoring (SHM) for the detection of damage in aerospace materials is an important area of research at NASA. Ultrasonic guided Lamb waves are a promising SHM damage detection technique since the waves can propagate long distances. For complicated flaw geometries experimental signals can be difficult to interpret. High performance computing can now handle full 3-dimensional (3D) simulations of elastic wave propagation in materials. We have developed and implemented parallel 3D elastodynamic finite integration technique (3D EFIT) code to investigate ultrasound scattering from flaws in materials. EFIT results have been compared to experimental data and the simulations provide unique insight into details of the wave behavior. This type of insight is useful for developing optimized experimental SHM techniques. 3D EFIT can also be expanded to model wave propagation and scattering in anisotropic composite materials

A Sonic Net Excludes Birds from an Airfield: Implications for Reducing Bird Strike and Crop Losses

Collisions between birds and aircraft cause billions of dollars of damages annually to civil, commercial, and military aviation. Yet technology to reduce bird strike is not generally effective, especially over longer time periods. Previous information from our lab indicated that filling an area with acoustic noise, which masks important communication channels for birds, can displace European Starlings (Sturnus vulgaris) from food sources. Here we deployed a spatially controlled noise (termed a “sonic net”), designed to overlap with the frequency range of bird vocalizations, at an airfield. By conducting point counts, we monitored the presence of birds for four weeks before deployment of our sonic net, and for four weeks during deployment. We found an 82% reduction in bird presence in the sonic net area compared with change in the reference areas. This effect was as strong in the fourth week of exposure as in the first week. We also calculated the potential costs avoided resulting from this exclusion. We propose that spatially controlled acoustic manipulations that mask auditory communication for birds may be an effective long term and fairly benign way of excluding problem birds from areas of socioeconomic importance, such as airfields, agricultural sites, and commercial properties

A Sonic Net Excludes Birds from an Airfield: Implications for Reducing Bird Strike and Crop Losses

Collisions between birds and aircraft cause billions of dollars of damages annually to civil, commercial, and military aviation. Yet technology to reduce bird strike is not generally effective, especially over longer time periods. Previous information from our lab indicated that filling an area with acoustic noise, which masks important communication channels for birds, can displace European Starlings (Sturnus vulgaris) from food sources. Here we deployed a spatially controlled noise (termed a “sonic net”), designed to overlap with the frequency range of bird vocalizations, at an airfield. By conducting point counts, we monitored the presence of birds for four weeks before deployment of our sonic net, and for four weeks during deployment. We found an 82% reduction in bird presence in the sonic net area compared with change in the reference areas. This effect was as strong in the fourth week of exposure as in the first week. We also calculated the potential costs avoided resulting from this exclusion. We propose that spatially controlled acoustic manipulations that mask auditory communication for birds may be an effective long term and fairly benign way of excluding problem birds from areas of socioeconomic importance, such as airfields, agricultural sites, and commercial properties