222,998 research outputs found
On cost-effective communication network designing
How to efficiently design a communication network is a paramount task for
network designing and engineering. It is, however, not a single objective
optimization process as perceived by most previous researches, i.e., to
maximize its transmission capacity, but a multi-objective optimization process,
with lowering its cost to be another important objective. These two objectives
are often contradictive in that optimizing one objective may deteriorate the
other. After a deep investigation of the impact that network topology, node
capability scheme and routing algorithm as well as their interplays have on the
two objectives, this letter presents a systematic approach to achieve a
cost-effective design by carefully choosing the three designing aspects. Only
when routing algorithm and node capability scheme are elegantly chosen can
BA-like scale-free networks have the potential of achieving good tradeoff
between the two objectives. Random networks, on the other hand, have the
built-in character for a cost-effective design, especially when other aspects
cannot be determined beforehand.Comment: 6 pages, 4 figure
Symmetrizable Quantum Affine Superalgebras And Their Representations
Aspects of the algebraic structure and representation theory of the quantum
affine superalgebras with symmetrizable Cartan matrices are studied. The
irreducible integrable highest weight representations are classified, and shown
to be deformations of their classical counterparts. It is also shown that Jimbo
type quantum affine superalgebras can be obtained by deforming universal
enveloping algebras of ordinary (i.e., non-graded) affine algebras supplemented
by certain parity operators.Comment: Latex, 14 page
The heavy-element abundances of AGB stars and the angular momentum conservation model of wind accretion for barium stars
Adpoting new s-process nucleosynthesis scenario and branch s-process path, we
calculate the heavy-element abundances and C/O ratio of solar metallicity
3M_sun TP-AGB stars. The evolutionary sequence from M to S to C stars of AGB
stars is explained naturally by the calculated results. Then combining the
angular momentum conservation model of wind accretion with the heavy-element
abundances on the surface of TP-AGB stars, we calculate the heavy-element
overabundances of barium stars via successive pulsed accreting and mixing. Our
results support that the barium stars with longer orbital period, P>1600 days,
form through wind accretion scenario.Comment: 14 pages, LaTex, 17 PS figures included, accepted for publication in
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