76,060 research outputs found
Synthesis of distributed systems Annual report, 1 Sep. 1967 - 31 Aug. 1968
Synthesis of distributed systems with application to feedback networks for phase shift oscillator
Synthesis of distributed systems Final report, 1 Sep. 1966 - 31 Aug. 1969
Algorithm for synthesis of distributed systems to solve circuit design problem
A Poset Connected to Artin Monoids of Simply Laced Type
Let W be a Weyl group whose type is a simply laced Dynkin diagram. On several
W-orbits of sets of mutually commuting reflections, a poset is described which
plays a role in linear representatons of the corresponding Artin group A. The
poset generalizes many properties of the usual order on positive roots of W
given by height. In this paper, a linear representation of the positive monoid
of A is defined by use of the poset
BMW algebras of simply laced type
It is known that the recently discovered representations of the Artin groups
of type A_n, the braid groups, can be constructed via BMW algebras. We
introduce similar algebras of type D_n and E_n which also lead to the newly
found faithful representations of the Artin groups of the corresponding types.
We establish finite dimensionality of these algebras. Moreover, they have
ideals I_1 and I_2 with I_2 contained in I_1 such that the quotient with
respect to I_1 is the Hecke algebra and I_1/I_2 is a module for the
corresponding Artin group generalizing the Lawrence-Krammer representation.
Finally we give conjectures on the structure, the dimension and parabolic
subalgebras of the BMW algebra, as well as on a generalization of deformations
to Brauer algebras for simply laced spherical type other than A_n.Comment: 39 page
Charge Transfer in Partition Theory
The recently proposed Partition Theory (PT) [J.Phys.Chem.A 111, 2229 (2007)]
is illustrated on a simple one-dimensional model of a heteronuclear diatomic
molecule. It is shown that a sharp definition for the charge of molecular
fragments emerges from PT, and that the ensuing population analysis can be used
to study how charge redistributes during dissociation and the implications of
that redistribution for the dipole moment. Interpreting small differences
between the isolated parts' ionization potentials as due to environmental
inhomogeneities, we gain insight into how electron localization takes place in
H2+ as the molecule dissociates. Furthermore, by studying the preservation of
the shapes of the parts as different parameters of the model are varied, we
address the issue of transferability of the parts. We find good transferability
within the chemically meaningful parameter regime, raising hopes that PT will
prove useful in chemical applications.Comment: 12 pages, 16 figure
Sheath ionization model of beam emissions from large spacecraft
An analytical model of the charging of a spacecraft emitting electron and ion beams has been applied to the case of large spacecraft. In this model, ionization occurs in the sheath due to the return current. Charge neutralization of spherical space charge flow is examined by solving analytical equations numerically. Parametric studies of potential large spacecraft are performed. As in the case of small spacecraft, the ions created in the sheath by the returning current play a large role in determining spacecraft potential
Diffuse radio emission in the merging cluster MACS J0717.5+3745: the discovery of the most powerful radio halo
Hierarchical models of structure formation predict that galaxy clusters grow
via mergers of smaller clusters and galaxy groups, as well as through
continuous accretion of gas. MACS J0717.5+3745 is an X-ray luminous and complex
merging cluster, located at a redshift of 0.55. Here we present Giant Metrewave
Radio Telescope (GMRT) radio observations at 610 MHz of this cluster. The main
aim of the observations is to search for diffuse radio emission within the
galaxy cluster MACS J0717.5+3745 related to the ongoing merger. These GMRT
observations are complemented by Very Large Array (VLA) archival observations
at 1.4, 4.9 and 8.5 GHz. We have discovered a radio halo in the cluster MACS
J0717.5+3745 with a size of about 1.2 Mpc. The radio power P_1.4 GHz is 5 x
10^25 W/Hz, which makes it the most powerful radio halo known till date. A 700
kpc radio structure, which we classify as a radio relic, is located in between
the merging substructures of the system. The location of this relic roughly
coincides with regions of the intra-cluster medium (ICM) that have a
significant enhancement in temperature as shown by Chandra. The major axis of
the relic is also roughly perpendicular to the merger axis. This shows that the
relic might be the result of a merger-related shock wave, where particles are
accelerated via the diffuse shock acceleration (DSA) mechanism. Alternatively,
the relic might trace an accretion shock of a large-scale galaxy filament to
the south-west. The global spectral index of radio emission within the cluster
is found to be -1.24 +/-0.05 between 4.9 GHz and 610 MHz. We derive a value of
5.8 microGauss for the equipartition magnetic field strength at the location of
the radio halo. [abridged].Comment: 8 pages, 9 figures, accepted for publication in A&A on August 3, 200
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