4,954 research outputs found
Computer program provides linear sampled- data analysis for high order systems
Computer program performs transformations in the order S-to W-to Z to allow arithmetic to be completed in the W-plane. The method is based on a direct transformation from the S-plane to the W-plane. The W-plane poles and zeros are transformed into Z-plane poles and zeros using the bilinear transformation algorithm
Direct and Indirect Searches for Low-Mass Magnetic Monopoles
Recently, there has been renewed interest in the search for low-mass magnetic
monopoles. At the University of Oklahoma we are performing an experiment
(Fermilab E882) using material from the old D0 and CDF detectors to set limits
on the existence of Dirac monopoles of masses of the order of 500 GeV. To set
such limits, estimates must be made of the production rate of such monopoles at
the Tevatron collider, and of the binding strength of any such produced
monopoles to matter. Here we sketch the still primitive theory of such
interactions, and indicate why we believe a credible limit may still be
obtained. On the other hand, there have been proposals that the classic
Euler-Heisenberg Lagrangian together with duality could be employed to set
limits on magnetic monopoles having masses less than 1 TeV, based on virtual,
rather than real processes. The D0 collaboration at Fermilab has used such a
proposal to set mass limits based on the nonobservation of pairs of photons
each with high transverse momentum. We critique the underlying theory, by
showing that the cross section violates unitarity at the quoted limits and is
unstable with respect to radiative corrections. We therefore believe that no
significant limit can be obtained from the current experiments, based on
virtual monopole processes.Comment: 20 pages, 1 ps figure, contributed to Kurt Haller's festschrif
Apparatus for remote handling of materials
Apparatus for remote handling of materials are described. A closed housing is provided with first and second containers and first and second reservoirs for holding materials to be mixed. The materials are transferable from the reservoirs to the first container where they are mixed. The mixed materials are then conveyed from the first container to the second container preferably by dumping the mixed materials into a funnel positioned over the second container. The second container is then moved to a second position for analysis of the mixed materials. For example, the materials may be ignited and the flame analyzed. Access, such as a sight port, is provided in the housing at the analysis position. The device provides a simple and inexpensive apparatus for safely mixing a pyrophoric material and an oxidizer which together form a thermite type mixture that burns to produce a large quantity of heat and light
Theoretical and Experimental Status of Magnetic Monopoles
The Tevatron has inspired new interest in the subject of magnetic monopoles.
First there was the 1998 D0 limit on the virtual production of monopoles, based
on the theory of Ginzberg and collaborators. In 2000 the first results from an
experiment (Fermilab E882) searching for real magnetically charged particles
bound to elements from the CDF and D0 detectors were reported. This also
required new developments in theory. The status of the experimental limits on
monopole masses will be discussed, as well as the limitation of the theory of
magnetic charge at present.Comment: 14 pages, 5 figures, talk given at 5th Workshop on Quantum Field
Theory Under External Condition
The Public Defender
A Review of The Public Defender by Lisa J. McIntyr
An Analysis of Residential Camp Site Structure !or Two Early Archaic Assemblages from Rose Island (40MR44), Tennessee
The site structure of two Early Archaic period assemblages is defined through spatial analysis of artifact and facility distributions at the Rose Island site (40MR44) in the lower Little Tennessee River valley. These assemblages derive from well controlled excavation of deeply buried alluvial deposits attributable to LeCroy (c. 6100-6500 B.C.) and St. Albans (c. 6600-7000 B.C.) temporal units. Spatial patterning is detected using multivariate statistical analysis of formal implement, instant tool, and debitage categories. The observed spatial patterns are interpreted through a comparison with expected spatial patterns generated from an a priori model of hunter-gatherer residential camp activity structure. The results of the analysis allow the proposal of a general model of Early Archaic residential camp site structure. The model identifies activity areas based upon densities and spatial relationships of artifact categories for an assemblage. The reconstructed activity structure describes the location of the family hearth as occurring in front of the opening of the shelter. A wide range of activities are localized around the family hearth. More specialized activities, such as flintworking, hideworking, and the roasting of game, are conducted near the shelter, but apart from the family hearth
Using the space-borne NASA scatterometer (NSCAT) to determine the frozen and thawed seasons
We hypothesize that the strong sensitivity of radar backscatter to surface dielectric properties, and hence to the phase (solid or liquid) of any water near the surface should make space-borne radar observations a powerful tool for large-scale spatial monitoring of the freeze/thaw state of the land surface, and thus ecosystem growing season length. We analyzed the NASA scatterometer (NSCAT) backscatter from September 1996 to June 1997, along with temperature and snow depth observations and ecosystem modeling, for three BOREAS sites in central Canada. Because of its short wavelength (2.14 cm), NSCAT was sensitive to canopy and surface water. NSCAT had 25 km spatial resolution and approximately twice-daily temporal coverage at the BOREAS latitude. At the northern site the NSCAT signal showed strong seasonality, with backscatter around −8 dB in winter and −12 dB in early summer and fall. The NSCAT signal for the southern sites had less seasonality. At all three sites there was a strong decrease in backscatter during spring thaw (4–6 dB). At the southern deciduous site, NSCAT backscatter rose from −11 to −9.2 dB during spring leaf-out. All sites showed 1–2 dB backscatter shifts corresponding to changes in landscape water state coincident with brief midwinter thaws, snowfall, and extreme cold (Tmax\u3c−25°C). Freeze/thaw detection algorithms developed for other radar instruments gave reasonable results for the northern site but were not successful at the two southern sites. We developed a change detection algorithm based on first differences of 5-day smoothed NSCAT backscatter measurements. This algorithm had some success in identifying the arrival of freezing conditions in the autumn and the beginning of thaw in the spring. Changes in surface freeze/thaw state generally coincided with the arrival and departure of the seasonal snow cover and with simulated shifts in the directions of net carbon exchange at each of the study sites
Blind Mans Buff Galop
https://digitalcommons.library.umaine.edu/mmb-ps/1410/thumbnail.jp
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