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Naraghi, M.

Publications and source records attributed to Naraghi, M..

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

A new interpretation of internal heat transfer coefficients of porous media

The results of laser anemometer and flow visualization based fluid mechanics studies of porous media are used to obtain heat transfer coefficients for porous materials. Average pore flow Re ranging from 0.16-700 were examined. Darcy, inertial steady laminar, unsteady laminar and turbulent flow regimes were detected. A passage length model was devised to derive the heat transfer coefficient. Sample data from flows through porous metals composed of powders and fibers validated the passage length for Darcy and inertial flow regimes. Unsteady laminar and turbulent flow coefficients require the identification of new parameters.

Dybbs, A.↗
NASA NTRS1984

Characteristics of playa deposits as seen on SIR-A, Seasat and Landsat coregistered data

A classification technique currently under development has been applied for the qualitative study of a playa located in Northeastern Algeria using coregistered SIR-A, Seasat and Landsat MSS 7 data. This classification which is texture based can be applied to only single band imagery at this time. The first results are very encouraging and reach conclusions similar to those obtained with more time consuming classifiers. The signature of each class is well expressed for the Landsat picture. Misclasifications occur with the SIR-A or Seasat images.

Rebillard, PH.↗
NASA NTRS1983

Bathymetric prediction from Seasat altimeter data

The linear response function technique is used to analyze two 1300 km tracks of Seasat altimeter data and corresponding bathymetry in the Musician Seamounts region north of Hawaii. A predictive filter is developed which can operate on Seasat altimetry in poorly surveyed oceanic regions to indicate the presence of major bathymetric anomalies. Modelling of the bathymetry-geoid correlation in the Musician region is attempted using the elastic plate model. The flexural rigidity of the plate is not well constrained by the data but appears to be in the range 5 x 10 to the 21st N m up to 5 x 10 to the 22nd N m at the time of loading. Since the Musician Seamounts and the crust on which they lie are both Late Cretaceous in age, this value represents the effective flexural rigidity of very young lithosphere that was 'frozen in' at the time of volcanism. The modelling indicates that the general form of a predictive filter will strongly depend on various geologic parameters, especially the effective flexural rigidity.

Dixon, T. H.↗
NASA NTRS1983

Geometric rectification of radar imagery using digital elevation models

Geologic analysis of radar imagery requires accurate spatial rectification to allow rock type discrimination and meaningful exploitation of multisensor data files. A procedure is described which removes distortions produced by most sources including the heretofore elusive problem of terrain induced effects. Rectified imagery is presented which displays geologic features not apparent in the distorted data.

Naraghi, M.↗
NASA NTRS1983

Autoregressive Models for Use in Scene Segmentation

A scene segmentation approach is presented which is based on generating autoregressive field models for each scene component (class) from its a priori spatial statistics. A methodology is also described for using these models in achieving optimal segmentation of a scene. The derivations are presented for the case of single band imagery, however, the method is believed to be extendable to multispectral data.

Naraghi, M.↗
NASA NTRS1983

Radar image registration and rectification

Two techniques for radar image registration and rectification are presented. In the registration method, a general 2-D polynomial transform is defined to accomplish the geometric mapping from one image into the other. The degree and coefficients of the polynomial are obtained using an a priori found tiepoint data set. In the second part of the paper, a rectification procedure is developed that models the distortion present in the radar image in terms of the radar sensor's platform parameters and the topographic variations of the imaged scene. This model, the ephemeris data and the digital topographic data are then used in rectifying the radar image. The two techniques are then used in registering and rectifying two examples of radar imagery. Each method is discussed as to its benefits, shortcomings and registration accuracy.

Naraghi, M.↗
NASA NTRS1982

Seasat/SIR-A digital registration over Algeria

Seasat Synthetic Aperture Radar (SAR) and Shuttle Imaging Radar (SIR-A) data over northeastern Algeria have been studied using digital registration. Preliminary results of this work show that: (1) both radars delineate in the same way the same features on the ground, (2) the Seasat image shows a strong difference between the Chott Melrhir and its environment, not seen in the same way by SIR-A, and (3) SIR-A data enhance more details on the floor of the Chotts, presumably due to the look angle or due to flooding conditions which may have occurred prior to the SIR-A experiment (November 12-14, 1981).

Rebillard, P.↗