217,648 research outputs found
A note on fragmentability and weak-G_delta sets
In terms of fragmentability, we describe a new class of Banach spaces which
do not contain weak-G_delta open bounded subsets. In particular, none of these
spaces is isomorphic to a separable polyhedral space
Monotonically improving approximate answers to relational algebra queries
We present here a query processing method that produces approximate answers to queries posed in standard relational algebra. This method is monotone in the sense that the accuracy of the approximate result improves with the amount of time spent producing the result. This strategy enables us to trade the time to produce the result for the accuracy of the result. An approximate relational model that characterizes appromimate relations and a partial order for comparing them is developed. Relational operators which operate on and return approximate relations are defined
Polynomial deformations of and generalized parabosons
We consider the algebra generated by three elements subject to
three relations , and . When this
coincides with the Lie superalgebra ; when is a polynomial we
speak of polynomial deformations of . Irreducible representations of
are described, and in the case we obtain a complete
classification, showing some similarities but also some interesting differences
with the usual representations. The relation with deformed
oscillator algebras is discussed, leading to the interpretation of as a
generalized paraboson algebra.Comment: 18 pages, LaTeX, TWI-94-X
Comprehension of familiar and unfamiliar native accents under adverse listening conditions
This study aimed to determine the relative processing cost associated with comprehension of an unfamiliar native accent under adverse listening conditions. Two sentence verification experiments were conducted in which listeners heard sentences at various signal-to-noise ratios. In Experiment 1, these sentences were spoken in a familiar or an unfamiliar native accent or in two familiar native accents. In Experiment 2, they were spoken in a familiar or unfamiliar native accent or in a nonnative accent. The results indicated that the differences between the native accents influenced the speed of language processing under adverse listening conditions and that this processing speed was modulated by the relative familiarity of the listener with the native accent. Furthermore, the results showed that the processing cost associated with the nonnative accent was larger than for the unfamiliar native accent
A MHD channel study for the ETF conceptual design
The procedures and computations used to identify an MHD channel for a 540 mW(I) EFT-scale plant are presented. Under the assumed constraints of maximum E(x), E(y), J(y) and Beta; results show the best plant performance is obtained for active length, L is approximately 12 M, whereas in the initial ETF studies, L is approximately 16 M. As MHD channel length is reduced from 16 M, the channel enthalpy extraction falls off, slowly. This tends to reduce the MHD power output; however, the shorter channels result in lower heat losses to the MHD channel cooling water which allows for the incorporation of more low pressure boiler feedwater heaters into the system and an increase in steam plant efficiency. The net result of these changes is a net increase in the over all MHD/steam plant efficiency. In addition to the sensitivity of various channel parameters, the trade-offs between the level of oxygen enrichment and the electrical stress on the channel are also discussed
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