Multidimensional Algebraic Polynomial Approximation

A computational algorithm to approximate an n-dimensional function of the form F(x,y,z, ...) by an algebraic polynomial in the least square (LSQ) sense is described. The basis of this algorithm is that the n-dimensional function can be approximated by a set of polynomials in each one of the independent variables x,y,z, ... . This technique is illustrated by deriving the algebraic polynomial approximation in the LSQ sense for three-dimensional functions of the form F(x,y,z).     

Merging Landsat and spaceborne radar data over Tunisia

Synthetic Aperture Radar data were acquired over Tunisia by Seasat in Aug. 1978 and by SIR-A in Nov. 1981. The radar images are contrasted to the Landsat scenes overlapping the same area. The Landsat images were taken in Aug. 1978 and in Sept. 1981. In this study, subareas of the SIR-A and MSS images are registered to the corresponding Seasat data (1313 lines by 1970 samples). The test site is located East of Kairouan, Tunisia. It is a low relief area with subdesertic climatic conditions. This region was selected for it has been surveyed by both Seasat and SIR-A providing perpendicular radar illumination directions. The multispectral and multitemporal coregistered data set enables comparisons between the systems (radar versus MSS, and Seasat versus SIR-A), and change detection in the desertification processes and on the surface of the playas.     

Contactless positioning,manipulation and shaping of liquids by gas bearing for microgravity applications

Contactless positioning, manipulation and shaping of liquids using the gas bearing principle is demonstrated by ground experiments. Extensions to microgravity applications are presented also associated with solidification of molten materials.     

The chromosphere-corona transition zone above an active region

Intensities and profiles of ion emission lines between 1170 A and 1700 A from an active region on the Sun are measured from spectra obtained with the Naval Research Laboratory's High Resolution Telescope and Spectrograph - HRTS. The measurements provide simultaneous determination of line intensities, wavelength shifts and Doppler widths at 50 separate positions in the active region, with spatial resolution of 1 arc second and spectral resolution 0.07 A. Fine structure variation of intensities and gas flow velocities in the temperature range 20,000–200,000 K are determined. The density sensitive line pair I(1486 N IV)/I(1548 C IV) has been used to measure electron pressures. Derived emission measures imply filling factors of 0.05–0.1 to balance the divergence of conductive flux width radiative losses above 60,000 K.     

Low-energy proton interaction with interplanetary magnetohydrodynamic discontinuities

Low energy proton measurements associated with interplanetary MHD discontinuities were detected by the DFH instrument on ISEE-3 spacecraft during the solar maximum period, September 1978–March 1980. The observations were made by three detectors, within eight sectors 45°wide each around the spacecraft, in eight energy channels extended from 35–1600Kev. They confirm that local magnetohydrodynamic conditions, especially discontinuities, significantly affect the propagation of low energy particles in the interplanetary medium.     

Observed and model N(h) profiles for the Bulgarian region

In this paper, combined bottom- and topside ionospheric N(h)-profiles are presented for the Bulgarian region. The profiles were constructed using ground (ionospheric observatories Sofia and Michurin) and satellite (Interkosmos-19) observations /1/.The observatories make quarter-hourly observations; in order to connect bottom and upper parts of the N(h) profile, we selected satellite orbits passing rather near to the observatory (zenith distance lsss than 100 km). Thus the time difference between ground station and satellite measurement was never more than 7.5 min.     

Sporadic emission of ultra high energy gamma rays from crab pulsar

In a further study of sporadic emission from pulsars we find evidence for short lived intense emission from the Crab pulsar.     

Properties of electrophoretic fractions of human embryonic kidney cells separated on Space Shuttle flight STS-8.

Suspensions of cultured primary human embryonic kidney cells were subjected to continuous flow electrophoresis on Space Shuttle flight STS-8. The objectives of the experiments were to obtain electrophoretically separated fractions of the original cell populations and to test these fractions for the amount and kind of urokinase (a kidney plasminogen activator that is used medically for digesting blood clots), the morphologies of cells in the individual fractions, and their cellular electrophoretic mobilities after separation and subsequent proliferation. Individual fractions were successfully cultured after return from orbit, and they were found to differ substantially from one another and from the starting sample with respect to all of these properties.     

Progress in the study of homologous flares on the sun — Part II

Studies of groups of homologous flares in active regions in 1980 have been made using a variety of space and ground based instruments. Detailed properties of three of these groups have been studied, and are combined to form a possible sequence of events.     

The incompressible zero-pressure-gradient turbulent boundary layer: An assessment of the data

The available data describing the incompressible zero-pressure-gradient boundary layer are reviewed in association with a range of studies which are either new or, to date, not very generally available. The new data cover a Reynolds number range 2.5 < Re_δ2 × 10⁻³ < 58 and include measurements of all three turbulence perlurbations and the Reynolds shear stress. They are assessed in relation to data in the range 0.4 < Re_δ2 × 10⁻³ < 211 using established scaling laws. In common with other investigators we find that while scaling the mean flow leads to a high degree of apparent similarity, scaling of the turbulence quantities is in general not so satisfactory.