8 research outputs found
Paper Session II-B - 3-Dimensional Feature Mapping Using Spatial Spectral Analysis
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
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
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
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