47,249 research outputs found
Olympus propagation studies in the US: Propagation terminal hardware and experiments
Virginia Tech is performing a comprehensive set of propagation measurements using the Olympus satellite beacons at 12.5, 20, and 30 GHz. These data will be used to characterize propagation conditions on small earth terminal (VSAT)-type networks for next generation small aperture Ka-band systems. The European Space Agency (ESA) satellite Olympus was launched July 12, 1989. The spacecraft contains a sophisticated package of propagation beacons operating at 12.5, 19.77, and 29.66 GHz (referred to as 12.5, 20, and 30 beacons). These beacons cover the east coast of the United States with sufficient power for attenuation measurements. The Virginia Satellite Communications Group is completing the hardware construction phase and will begin formal data collection in June
Crawling Water Beetles of Wisconsin (Coleoptera: Haliplidae)
(excerpt)
Haliplidae are smail water beetles, less than 5 mm long, that frequently occur in abundance in ponds, marshes, sloughs, and swamps and also along the margins of slow streams or lakes where there is not severe wave action. Adults are readily recognized by their yelloa- to orange ground color with black maculations on the elytra and sometimes on the head and pronotum (Figs. 1,3,4). They have a distinctive shape, being broadest at the basss of the elytra and tapered toward the posterior end. The metacoxae are covered by dis~ctive plates that are unique among water beetles (Fig. 2). The tarsi and tibiae of the adults are modified for swimming, and the beetles can swim quite well, although they mostly crawl among the vegetation. Adults and larvae are found among vegetation upon which they feed, filamentous algae being the primary source of food for most species, but detrims and animal material may form a portion of the diet in some species. In Wisconsin most species probably have a one-year life cycle and overwinter as adults. Eggs are laid during spring and early summer, usually in or upon algae. There are three larval instars, and pupation takes place in moist soil above the water line. Larvae have been derrihd for only a few species, so identification is based upon adult characteristics
Compliant hydrodynamic fluid journal bearing
An air bearing structure is described that prevents destructive bending moments within the top foil. Welds are eliminated by mounting the top bearing foil in the bearing cartridge sleeve without using a space block. Tabs or pins at the end of the top bearing foil are restrained by slots or stops formed in the cartridge sleeve. These structural members are free to move in a direction normal to the shaft while being restrained from movement in the direction of shaft rotation
ACTS propagation terminal update
The activities at Virginia Polytechnic Institute and State University in preparation for the February 1993 launch of ACTS are summarized. ACTS propagation terminals (APT) are being constructed to receive the 20 and 27.5 GHz ACTS beacon signals. Total power radiometers operating at the same frequencies are integrated into the terminal for use in level setting. Recent progress and plans for APT's are reported
Evaluating research - Peer review team assessment and journal-based bibliographic measures: New Zealand PBRF research output scores in 2006
This paper concerns the relationship between the assessment of the research of individual academics by peer or expert review teams with a variety of bibliometric schemes based on journal quality weights. Specifically, for a common group of economists from New Zealand departments of economics the relationship between Performance-Based Research Fund (PBRF) Research Output measures for those submitting new research portfolios in 2006 are compared with evaluations of journal based research over the 2000-2005 assessment period. This comparison identifies the journal weighting schemes that appear most similar to PBRF peer evaluations. The paper provides an indication of the ‘power or aggressiveness’ of PBRF evaluations in terms of the weighting given to quality. The implied views of PBRF peer review teams are also useful in assessing common assumptions made in evaluating journal based research
Constructing two-sided simultaneous confidence intervals for multinomial proportions for small counts in a large number of cells
Confidence intervals for multinomial proportions are often constructed using large-sample methods that rely on expected cell counts of 5 or greater. In situations that give rise to a large number of categories, the cell counts may not be of adequate size to ensure the appropriate overall coverage probability and alternative methods of construction have been proposed. Sison and Glaz (1995) developed a method of constructing two-sided confidence intervals for multinomial proportions that is based on the doubly truncated Poisson distribution and their method performs well when the cell counts are fairly equally dispersed over a large number of categories. In fact, the Sison and Glaz (1995) intervals appear to outperform other methods of simultaneous construction in terms of coverage probabilities and interval length in these situations. To make the method available to researchers, we have developed a SAS macro to construct the intervals proposed by Sison and Glaz (1995).
NASA propagation information center
The NASA Propagation Information Center became formally operational in July 1988. It is located in the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. The center is several things: a communications medium for the propagation with the outside world, a mechanism for internal communication within the program, and an aid to management
NASA Propagation Information Center
The NASA Propagation Information Center became formally operational in July 1988. It is located in the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. The Center is several things: a communications medium for the propagation with the outside world, a mechanism for internal communication within the program, and an aid to management
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