1,485 research outputs found
Low sidelobe level low-cost earth station antennas for the 12 GHz broadcasting satellite service
An experimental investigation of the performance of 1.22 m and 1.83 m diameter paraboloid antennas with an f/D ratio of 0.38 and using a feed developed by Kumar is reported. It is found that sidelobes below 30 dB can be obtained only if the paraboloids are relatively free of surface errors. A theoretical analysis of clam shell distortion shows that this is a limiting factor in achieving low sidelobe levels with many commercially available low cost paraboloids. The use of absorbing pads and small reflecting plates for sidelobe reduction is also considered
Similarity Measure Development for Case-Based Reasoning- A Data-driven Approach
In this paper, we demonstrate a data-driven methodology for modelling the
local similarity measures of various attributes in a dataset. We analyse the
spread in the numerical attributes and estimate their distribution using
polynomial function to showcase an approach for deriving strong initial value
ranges of numerical attributes and use a non-overlapping distribution for
categorical attributes such that the entire similarity range [0,1] is utilized.
We use an open source dataset for demonstrating modelling and development of
the similarity measures and will present a case-based reasoning (CBR) system
that can be used to search for the most relevant similar cases
Ensiling of Tannin-Containing Sorghum Grain
Sorghum is known as important feed-stuff in tropical regions where rainfall is insufficient for the cultivation of maize. Furthermore, those sorghum cultivars rich in tannins are naturally protected to a certain extent against bird damage, insect pests and moulds. Nevertheless, tannins impair the feed quality. Thus, the objectives of this study were to investigate whether ensiling could be a suitable preservation method for sorghum grain originally rich in tannins and if it is possible to reduce tannin content during fermentation
A new method for microscale cyclic crack growth characterization from notched microcantilevers and application to single crystalline tungsten and a metallic glass
The lifetime of most metals is limited by cyclic loads, ending in fatigue
failure. The progressive growth of cracks ends up in catastrophic failure. An
advanced method is presented for the determination of cyclic crack growth on
the microscale using a nanoindenter, which allows the characterization of >
10,000 loading cycles. It uses focused ion beam fabricated notched
microcantilevers. The method has been validated by cyclic bending metallic
glass and tungsten microcantilevers. The experiments reveal a stable crack
growth during the lifetime of both samples. The metallic glass shows less
plasticity due to the absence of dislocations, but shows shearing caused by the
deformation. The crack growth rates determined in the tests follow Paris' power
law relationship. The results are reliable, reproducible and comparable with
macroscopic setups. Due to the flexibility of the method, it is suitable for
the characterization of specific microstructural features, like single phases,
grain boundaries or different grain orientations
Nursery Plants Available from South Dakota Nurseries
This publications is prepared as a guide for locating specific nursery items that may be available from South Dakota nurseries and garden centers. The list is intended for use in locating plants primarily by nurseries, horticulturists, foresters, conservationists, Cooperative Extension Service personnel, and other advisors
Antarctic meteorite newsletter. Volume 4: Number 1, February 1981: Antarctic meteorite descriptions, 1976, 1977, 1978, 1979
This issue of the Newsletter is essentially a catalog of all antarctic meteorites in the collections of the Johnson Space Center Curation Facility and the Smithsonian except for 288 pebbles now being classed. It includes listings of all previously distributed data sheets plus a number of new ones for 1979. Indexes of samples include meteorite name/number, classification, and weathering category. Separate indexes list type 3 and 4 chondrites, all irons, all achondrites, and all carbonaceous chondrites
Antarctic meteorite descriptions 1976-1977-1978-1979
All previously distributed meteorite data sheets, plus a number of new ones for 1979 chondrites are included. A comprehensive sample index listing meteorite name/number, classification, and weathering category is also included. Separate indexes listing all petrologic type 3 and type 4 chondrites, all irons, all achondrites, and all carbonaceous chondrites in the collection is provided
Variable Intrinsic Absorption in Mrk 279
We examine the variability in the intrinsic absorption in the Seyfert 1
galaxy Mrk 279 using three epochs of observations from the Far Ultraviolet
Spectroscopic Explorer (FUSE) and two epochs of observations with the Space
Telescope Imaging Spectrograph on the Hubble Space Telescope. Rather than
finding simple photoionization responses of the absorbing gas to changes in the
underlying continuum, the observed changes in the absorption profiles can be
understood more clearly if the effective covering fraction of the gas in all
emission components, continuum and broad and intermediate velocity width
emission lines, is accounted for. While we do not uniquely solve for all of
these separate covering fractions and the ionic column densities using the
spectral data, we examine the parameter space using previously well-constrained
solutions for continuum and single emission component covering fractions.
Assuming full coverage of the continuum, we find that of the two velocity
components of the Mrk 279 absorption most likely associated with its outflow,
one likely has zero coverage of the intermediate line region while the other
does not. For each component, however, the broad line region is more fully
covered than the intermediate line region. Changes in the O VI column densities
are unconstrained due to saturation, but we show that small changes in the
nonsaturated C IV and N V column densities are consistent with the outflow gas
having zero or partial covering of the intermediate line region and an
ionization parameter changing from ~0.01 to ~0.1 from 2002 to 2003 as the UV
continuum flux increased by a factor of ~8. The absence of a change in the C
III absorbing column density is attributed to this species arising outside the
Mrk 279 outflow.Comment: 36 pages, 18 figures, accepted to Ap
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