Ordered Covering Arrays and Upper Bounds on Covering Codes in NRT spaces

This work shows several direct and recursive constructions of ordered covering arrays using projection, fusion, column augmentation, derivation, concatenation and cartesian product. Upper bounds on covering codes in NRT spaces are also obtained by improving a general upper bound. We explore the connection between ordered covering arrays and covering codes in NRT spaces, which generalize similar results for the Hamming metric. Combining the new upper bounds for covering codes in NRT spaces and ordered covering arrays, we improve upper bounds on covering codes in NRT spaces for larger alphabets. We give tables comparing the new upper bounds for covering codes to existing ones.Comment: 27 page

Aeronautical Engineering: A special bibliography with indexes, supplement 51

This bibliography lists 206 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in November 1974

Extracting cosmological signals from foregrounds in deep mm maps of the sky

The high Galactic latitude sky at millimeter and submm wavelengths contains significant cosmological information about the early Universe (in terms of the cosmic microwave background) but also the process of structure formation in the Universe from the far infrared background produced by early galaxies and the Sunyaev-Zeldovich effect in clusters of galaxies. As the Planck mission will produce full sky maps in this frequency range, deeper maps of selected low-foregrounds patches of the sky can produce complementary and important information. Here we analyze the performance of a balloon-borne survey covering a 10^\circ x 10^\circ patch of the sky with a few arcminute resolution and very high pixel sensitivity. We simulate the different components of the mm/submm sky (i.e., CMB anisotropies, SZ effect, radio and infrared sources, far infrared background, and interstellar dust) using current knowledge about each of them. We then combine them, adding detector noise, to produce detailed simulated observations in four observational bands ranging from 130 to 500 GHz. Finally, we analyze the simulated maps and estimate the performance of the instrument in extracting the relevant information about each of the components. We find that the CMB angular power spectrum is accurately recovered up to l ~ 3000. Using the Sunyaev-Zel'dovich effect, most of the galaxy clusters present in our input map are detected (60% efficiency overall). Our results also show that much stronger constrains can be placed on far infrared background models.Comment: 10 pages, 8 figures, accepted for publication in A&

Aeronautical Engineering: A special bibliography with indexes, supplement 72, July 1976

This bibliography lists 184 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1976

MAX '91: An advanced payload for the exploration of high energy processes on the active sun

The results of a NASA science working group established to study a follow-on to the Solar Maximum Mission are given. A complement of instruments is suggested, with the primary objective of studying the physics of energetic processes in cosmic plasmas by observing high-energy phenomena in solar flares. High-quality flare observations will be possible with these instruments during the next peak in solar activity expected to last from 1990 through at least 1995. The primary objective of MAX '91 is to study energetic processes in cosmic plasmas by observing high-energy phenomena in solar flares. These processes, which are of general astrophysical importance, include energy release, particle acceleration, and energy transport. Results from comprehensive observing programs conducted during the last solar cycle have demonstrated the great scientific potential of high-energy emissions for addressing these central physical processes. Consequently, a payload optimized for observations of high-energy solar flare phenomena is suggested for MAX '91. It consists of the following four specific instruments: (1) a Fourier-transform X-ray and gamma-ray imager covering the energy range from a few keV to 1 MeV with arcsecond spatial resolution; (2) a cooled germanium X-ray and gamma-ray spectrometer with keV spectral resolution covering the energy range from 10 keV to 50 MeV; (3) Bragg spectrometers with high spectral resolution at wavelengths between 1 and 9 angstrons; and (4) a soft X-ray, EUV, or UV imaging instrument with arcsecond spatial resolution

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences