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  • 1
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    Remote determination of the two-dimensional diffusivity tensor in thin plates (1987)
    In:  CASI
    Details
    Publication Date: 2004-10-30
    Keywords: STRUCTURAL MECHANICS
    Type: NDE at NASA Langley. Advancing the State-of-the-Art and Providing a Quantitative Science Base for Materials Characterization; 4 p
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  • 2
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    Quantitative thermal characterization of thin plates (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The principles of quantitative thermal testing of the mechanical integrity of platelike structures are discussed. In this technique, a scanned laser pulse is used to inject a thermal pattern in a sample, and a thermal IR imager is used to document the evolution of the pattern subsequent to injection. The measurements are remote, noncontacting, and one-sided, and the algorithms used to obtain diffusivity are all emissivity-independent. The results yielded by application of the three analytical techniques, used to obtain diffusivity values from the image data on stainless steel, a graphite-epoxy composite, brass, and aluminum 2024 samples, are presented.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
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  • 3
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    Quantitative thermal diffusivity measurements of composites (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A remote radiometric technique for making quantitative thermal diffusivity measurements is described. The technique was designed to make assessments of the structural integrity of large composite parts, such as wings, and can be performed at field sites. In the measurement technique, a CO2 laser beam is scanned using two orthogonal servo-controlled deflecting mirrors. An infrared imager, whose scanning mirrors oscillate in the vertical and the horizontal directions, is used as the detector. The analysis technique used to extract the diffusivity from these images is based on a thin infinite plate assumption, which requires waiting a given period of time for the temperature to equilibrate throughout the thickness of the sample. The technique is shown to be accurate to within two percent for values of the order of those for composite diffusivities, and to be insensitive to convection losses.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
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  • 4
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    The design and development of a third generation OSEE instrument (1995)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Optically Stimulated Electron Emission (OSEE) has been used to quantify surface contamination in the aerospace community. As advances are made towards the understanding of OSEE, it is desirable to incorporate technological advances with succeeding generations of instrumentation, so that improvements in the practical application of OSEE may be disseminated among the user community. Several studies undertaken by Yost, Welch, Abedin and others have expanded the knowledge base related to the underlying principles of OSEE. The conclusions of these studies, together with inputs from the user community were the foundation upon which the development of a third generation OSEE instrument was based. This manuscript describes the significant improvements incorporated into a third generation OSEE instrument as well as the elements unique to its design.
    Keywords: OPTICS
    Type: NASA. Marshall Space Flight Center, Aerospace Environmental Technology Conference; p 533-540
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  • 5
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    OSEE responses on D6AC steel due to sample preparation (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A cleaning procedure and a contamination method developed at NASA Langley to contaminate sample surfaces with a certain thickness of HD-2 grease are demonstrated. Varying levels of contamination are obtained. Optically stimulated electron emission (OSEE) measurements were performed using the parallel electric field cell and the Pat scan device for clean and contaminated samples with a known amount of common contaminant. The OSEE response is found to be more sensitive for the clean sample than for the contaminated one. It is concluded that the OSEE measurements obtained using these techniques are sensitive to surface conditions and the contaminant thickness variations. It is also shown that the wavelength of illuminating light can have a profound effect on OSEE current levels.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
    Type: In: Review of progress in quantitative nondestructive evaluation. Vol. 11B; Proceedings of the 18th Annual Review, Brunswick, ME, July 28-Aug. 2, 1991 (A93-19582 06-38); p. 1799-1805.
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  • 6
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    On the use of drift bottle and seabed drifter data in coastal management (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The use of drift bottle and seabed drifter information for use in coastal management is discussed. The drift bottle/seabed drifter portion of VIMS project MACONS (Mid Atlantic Continental Shelf) is described as an example of how a comprehensive survey using drift bottles and seabed drifters provides data useful for coastal management. The data from MACONS are analyzed to answer specific questions of interest to several different coastal managers: a manager siting a deep oil port, one siting a sewage outfall, a manager responsible for setting up emergency beach protection procedures before an accident occurs, and a manager responsible for the environmental quality of a particular small section of coastline.
    Keywords: GEOPHYSICS
    Type: NASA-CR-136939 , VIMS-CONTRIB-571 , REPT-44
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  • 7
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    Applications of remote sensing to estuarine management (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Projects for sewage outfall siting for pollution control in the lower Chesapeake Bay wetlands are reported. A dye-buoy/photogrammetry and remote sensing technique was employed to gather circulation data used in outfall siting. This technique is greatly favored over alternate methods because it is inexpensive, produces results quickly, and reveals Lagrangian current paths which are preferred in making siting decisions. Wetlands data were obtained by interpretation of color and color infrared photographic imagery from several altitudes. Historical sequences of photographs are shown that were used to document wetlands changes. Sequential infrared photography of inlet basins was employed to determine tidal prisms, which were input to mathematical models to be used by state agencies in pollution control. A direct and crucial link between remote sensing and management decisions was demonstrated in the various projects.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA-CR-148826 , AR-4
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  • 8
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    Application of remote sensing to study nearshore circulation (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Immediate use of drogued buoy tracking was made when the Virginia State Highway Department requested assistance in selecting the best route for a new bridge-tunnel complex across the James River at Newport News. The result was that the Highway Department acted and chose a preferred route from several alternatives. It was also observed that the drogues did not follow the channel as predicted by the James River hydraulic model. This permitted telling the Navy why it is that part of their channel always silts up. The Hampton Roads Sanitation District asked help locate the best route and position of an ocean sewer outfall. Biological activities are focused primarily on delineating biological interaction between the marsh and continental shelf waters on Virginia's Eastern Shore. Information derived is helpful in categorizing the relative biological value of different marsh areas so that meaningful use and management decisions can be made concerning their eventual disposition.
    Keywords: GEOPHYSICS
    Type: NASA-CR-135827 , AR-1
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  • 9
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    Outfall siting with dye-buoy remote sensing of coastal circulation (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A dye-buoy remote sensing technique has been applied to estuarine siting problems that involve fine-scale circulation. Small hard cakes of sodium fluorescein and polyvinyl alcohol, in anchored buoys and low-windage current followers, dissolve to produce dye marks resolvable in 1:60,000 scale color and color infrared imagery. Lagrangian current vectors are determined from sequential photo coverage. Careful buoy placement reveals surface currents and submergence near fronts and convergence zones. The technique has been used in siting two sewage outfalls in Hampton Roads, Virginia: In case one, the outfall region during flood tide gathered floating materials in a convergence zone, which then acted as a secondary source during ebb; for better dispersion during ebb, the proposed outfall site was moved further offshore. In case two, flow during late flood was found to divide, with one half passing over shellfish beds; the proposed outfall site was consequently moved to keep effluent in the other half.
    Keywords: OCEANOGRAPHY
    Type: Photogrammetric Engineering and Remote Sensing; 44; Jan. 197
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  • 10
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    Quantitative non-destructive testing (1985)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The work undertaken during this period included two primary efforts. The first is a continuation of theoretical development from the previous year of models and data analyses for NDE using the Optical Thermal Infra-Red Measurement System (OPTITHIRMS) system, which involves heat injection with a laser and observation of the resulting thermal pattern with an infrared imaging system. The second is an investigation into the use of the thermoelastic effect as an effective tool for NDE. As in the past, the effort is aimed towards NDE techniques applicable to composite materials in structural applications. The theoretical development described produced several models of temperature patterns over several geometries and material types. Agreement between model data and temperature observations was obtained. A model study with one of these models investigated some fundamental difficulties with the proposed method (the primitive equation method) for obtaining diffusivity values in plates of thickness and supplied guidelines for avoiding these difficulties. A wide range of computing speeds was found among the various models, with a one-dimensional model based on Laplace's integral solution being both very fast and very accurate.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
    Type: NASA-CR-176761 , NAS 1.26:176761
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