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  • 1
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    A method for classification of multisource data using interval-valued probabilities and its application to HIRIS data (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A method of classifying multisource data in remote sensing is presented. The proposed method considers each data source as an information source providing a body of evidence, represents statistical evidence by interval-valued probabilities, and uses Dempster's rule to integrate information based on multiple data source. The method is applied to the problems of ground-cover classification of multispectral data combined with digital terrain data such as elevation, slope, and aspect. Then this method is applied to simulated 201-band High Resolution Imaging Spectrometer (HIRIS) data by dividing the dimensionally huge data source into smaller and more manageable pieces based on the global statistical correlation information. It produces higher classification accuracy than the Maximum Likelihood (ML) classification method when the Hughes phenomenon is apparent.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA, Goddard Space Flight Center, Multisource Data Integration in Remote Sensing; p 75-81
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  • 2
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    Observations of the frequencies in a sphere wake and of drag increase by acoustic excitation (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Vortex shedding and instability wave frequencies have been measured in the wakes of spheres in the Reynolds number range 500 less than Re less than 60,000. The effect of acoustic excitation was examined and an interaction between the two frequency modes was found at the lower Reynolds numbers; through this interaction, external forcing at the instability frequency could change the vortex shedding frequency. The development of the mean wake was manipulated by forcing near to the dominant shear layer instability frequency. With this forcing, the separated shear layer moved closer to the surface of the sphere and the reversed flow region of the wake was shortened. Concomitantly, the base pressure decreased and drag increased.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 31; 3260-326
    Format: text
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  • 3
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    Investigation of the flow between a pair of circular cylinders in the flopping regime (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The wakes of a pair of circular cylinders are grossly unsteady when the cylinders are separated in a direction normal to the approaching flow by less than one cylinder diameter. The wakes flop randomly between two asymmetric states. The time-scale for the flopping is several orders of magnitude longer than the timescale of vortex shedding, and also several orders of magnitude longer than the timescale for instability of the separating shear layers. When a splitter plate is positioned suitably on the centerline of the cylinders, the flopping can be stopped and the flow made to assume either of the asymmetric states, or a symmetric steady state. For a range of plate positions a new, periodic oscillation occurs. Acoustic excitation can also destroy the flopping mean flow, replacing it by a symmetric flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 196; 431-448
    Format: text
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  • 4
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    An iterative implicit DDADI algorithm for solving the Navier-Stokes equation (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: An algorithm utilizing a first order upwind split flux technique and the diagonally dominant treatment is proposed to be the temporal operator for solving the Navier-Stokes equations. Given the limit of a five point stencil, the right hand side flux derivatives are formulated by several commonly used central and upwind schemes. Their performances are studied through a test case of free vortex convection in a uniform stream. From these results, a superior treatment for evaluating the flux term is proposed and compared with the rest. The application of the proposed algorithm to the full Navier-Stokes equations is demonstrated through a calculation of flow over a backward facing step. Results are compared against the calculation done by using the fourth order central differencing scheme with artificial damping.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Fluid Dynamics; p 29-46
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  • 5
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    A method for classification of multisource data using interval-valued probabilities and its application to HIRIS data (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A method of classifying multisource data in remote sensing is presented. The proposed method considers each data source as an information source providing a body of evidence, represents statistical evidence by interval-valued probabilities, and uses Dempster's rule to integrate information based on multiple data sources. The method is applied to the problems of ground-cover classification of multispectral data combined with digital terrain data such as elevation, slope, and aspect. Then this method is applied to simulated 201-band High Resolution Imaging Spectrometer (HIRIS) data by dividing the dimensionally huge data source into smaller and more manageable pieces based on the global statistical correlation information. It produces higher classification accuracy than the Maximum Likelihood (ML) classification method when the Hughes phenomenon is apparent.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Format: text
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  • 6
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    Combining multispectral and ancillary data in remote sensing using interval-valued probabilities (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This paper presents a method for classifying multisource data in remote sensing and geographic information systems using interval-valued probabilities. In this method, each data source is considered as an information source which provides a body of statistical evidence. In order to integrate information obtained from multiple data sources, the method adopts Dempster's rule for combining multiple bodies of evidence. Preliminary experiments have been undertaken to illustrate the use of the method in a supervised ground-cover classification on multispectral data combined with digital elevation data. They demonstrate the ability of the method in capturing information provided by inexact and incomplete evidence when there are not enough training samples to estimate statistical parameters.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 7
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    Spanwise structures in transitional flow around circular cylinders (1987)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An experimental investigation of the flow around a smooth circular cylinder at the beginning of the critical transition, where the drag coefficient starts to decrease, was carried out. The measurements disclosed the presence of spanwise structures occurring symmetrically on both sides of the cylinder, associated with large amplitude, low frequency flow components. Mean pressure maps and spanwise cross correlations of pressures and velocities are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 87-1383
    Format: text
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  • 8
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    Ocean Chlorophyll Studies from a U-2 Aircraft Platform (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Chlorophyll gradient maps of large ocean areas were generated from U-2 ocean color scanner data obtained over test sites in the Pacific and Atlantic Oceans. The delineation of oceanic features using the upward radiant intensity relies on an analysis method which presupposes that radiation backscattered from the atmosphere and ocean surface can be properly modeled using a measurement made at 778 nm. An estimation of the chlorophyll concentration was performed by properly ratioing radiances measured at 472 nm and 548 nm after removing the atmospheric effects. The correlation between the remotely sensed data and in-situ surface chlorophyll measurements was validated in two sets of data. The results show that the correlation between the in-situ measured chlorophyll and the derived quantity is a negative exponential function and the correlation coefficient was calculated to be -0.965.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: NASA-TM-80574
    Format: application/pdf
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