8 research outputs found

    Paper Session II-B - 3-Dimensional Feature Mapping Using Spatial Spectral Analysis

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    Orbiter vehicles are routinely exposed to a variety of small scale debris while operating in low earth orbit. Impacts with such debris often result in surface and/or subsurface damage to orbiter windows. Current procedures require windows to be manually inspected for impact damage after each shuttle mission. Once identified, surface damage feature depths are determined by analyzing mold impressions of the damaged areas. Subsurface damage always results in window rejection since the depths of subsurface features are deemed unmeasurable using standard mold impression measurement techniques. This paper presents an automated optical technique for measuring the depth of small scale surface and subsurface damage features in orbiter windows. Test results based on actual orbiter window damage features are also presented

    Paper Session III-B - Ultrasonic Correlation Bolt Tension Analyzer

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    We describe our efforts in the development of an improved ultrasonic bolt tension analyzer (bolt gage) for use in precision tensioning of bolts in critical applications. This new instrument uses correlation techniques to ameliorate the peak jumping problems usually associated with ultrasonic bolt gages. Our instrument has been put through substantial (though not exhaustive) tests, with very good results

    Paper Session I-C - Non-Destructive Detection of Corrosion Under Paint on Critical Surfaces

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    We describe our proof-of-concept demonstration of the well-known thermal diffusion imaging technique *\u3e 2\u3e3 for detection of corrosion under paint on critical surfaces. Our first application will be the detection and mapping of corrosion on arbiter vehicle wing spars and rudder speed brakes. The technique will also used for the evaluation of doubler plate bond integrity on the rudder speed brakes

    Complex patterns of global spread in invasive insects: eco-evolutionary and management consequences

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    The advent of simple and affordable tools for molecular identification of novel insect invaders and assessment of population diversity has changed the face of invasion biology in recent years. The widespread application of these tools has brought with it an emerging understanding that patterns in biogeography, introduction history and subsequent movement and spread of many invasive alien insects are far more complex than previously thought. We reviewed the literature and found that for a number of invasive insects, there is strong and growing evidence that multiple introductions, complex global movement, and population admixture in the invaded range are commonplace. Additionally, historical paradigms related to species and strain identities and origins of common invaders are in many cases being challenged. This has major consequences for our understanding of basic biology and ecology of invasive insects and impacts quarantine, management and biocontrol programs. In addition, we found that founder effects rarely limit fitness in invasive insects and may benefit populations (by purging harmful alleles or increasing additive genetic variance). Also, while phenotypic plasticity appears important post-establishment, genetic diversity in invasive insects is often higher than expected and increases over time via multiple introductions. Further, connectivity among disjunct regions of global invasive ranges is generally far higher than expected and is often asymmetric, with some populations contributing disproportionately to global spread. We argue that the role of connectivity in driving the ecology and evolution of introduced species with multiple invasive ranges has been historically underestimated and that such species are often best understood in a global context

    Complex patterns of global spread in invasive insects: eco-evolutionary and management consequences

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