31,504 research outputs found
[Colored solutions of Yang-Baxter equation from representations of U_{q}gl(2)]
We study the Hopf algebra structure and the highest weight representation of
a multiparameter version of . The commutation relations as well as
other Hopf algebra maps are explicitly given. We show that the multiparameter
universal matrix can be constructed directly as a quantum double
intertwiner, without using Reshetikhin's transformation. An interesting feature
automatically appears in the representation theory: it can be divided into two
types, one for generic , the other for being a root of unity. When
applying the representation theory to the multiparameter universal
matrix, the so called standard and nonstandard colored solutions of the Yang-Baxter equation is obtained.Comment: [14]pages, latex, no figure
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Experimental study on a small-scale R245fa organic Rankine cycle system for low-grade thermal energy recovery
This work conducted an experimental investigation of a small-scale organic Rankine cycle (ORC) system at designed operating and control conditions for low-grade thermal energy recovery application. In the ORC system, R245fa was selected as working fluid while a turboexpander (turbine) with a high speed and permanent magnet synchronous electricity generator was installed to produce electric power and two-plate type heat exchangers were designed as an evaporator and condenser. The effects of condenser cooling water temperatures and R245fa superheat at the turbine inlet on the system performance were measured and analyzed. Practically, to ensure safe operation of the ORC expander, the R245fa superheat at the expander inlet is controlled to remain constant. The experimental results showed that at constant heat source parameters (temperature and flow rate), the turboexpander power output and cycle efficiency increased with lower cooling water temperatures. Under the specified test condition ranges, the maximum turboexpander power generation could achieve 5.405 kW when the cooling water temperature and the pressure ratio were set at 23.0°C and 7.3 respectively. On the other hand, at certain cooling water temperatures, the superheat at the expander inlet exerted a negative impact on the turboexpander and system performances when the evaporating pressure was kept constant. Ultimately, the superheat was found to be an important control parameter to ensure efficient and safe system operation
Local U(1) symmetry in Y(so(5)) associated with Massless Thirring Model and its Bethe Ansatz
The Massless Thirring model associated with SO(5) is solved in terms of the
local U(1) symmetry. The local U(1) symmetry is related to q-deformation of
four-component field operators due to the nonlinear interaction for differently
internal degree of freedom. The Bethe ansatz wavefunction is also discussed. In
addition, the local U(1) symmetry in the Yangian associated with
SO(5)(Y(SO(5))) is explored.Comment: 10 pages, no figure
Acoustic black holes from supercurrent tunneling
We present a version of acoustic black holes by using the principle of the
Josephson effect. We find that in the case two superconductors and are
separated by an insulating barrier, an acoustic black hole may be created in
the middle region between the two superconductors. We discuss in detail how to
describe an acoustic black hole in the Josephson junction and write the metric
in the langauge of the superconducting electronics. Our final results infer
that for big enough tunneling current and thickness of the junction,
experimental verification of the Hawking temperature could be possible.Comment: 15pages,1 figure, to appear in IJMP
Anisotropic but nodeless superconducting gap in the presence of spin density wave in iron-pnictide superconductor NaFe1-xCoxAs
The coexisting regime of spin density wave (SDW) and superconductivity in the
iron pnictides represents a novel ground state. We have performed high
resolution angle-resolved photoemission measurements on NaFe1-xCoxAs (x =
0.0175) in this regime and revealed its distinctive electronic structure, which
provides some microscopic understandings of its behavior. The SDW signature and
the superconducting gap are observed on the same bands, illustrating the
intrinsic nature of the coexistence. However, because the SDW and
superconductivity are manifested in different parts of the band structure,
their competition is non-exclusive. Particularly, we found that the gap
distribution is anisotropic and nodeless, in contrast to the isotropic
superconducting gap observed in an SDW-free NaFe1-xCoxAs (x=0.045), which puts
strong constraints on theory.Comment: 5 pages, 4 figures + supplementary informatio
Hierarchic Superposition Revisited
Many applications of automated deduction require reasoning in first-order
logic modulo background theories, in particular some form of integer
arithmetic. A major unsolved research challenge is to design theorem provers
that are "reasonably complete" even in the presence of free function symbols
ranging into a background theory sort. The hierarchic superposition calculus of
Bachmair, Ganzinger, and Waldmann already supports such symbols, but, as we
demonstrate, not optimally. This paper aims to rectify the situation by
introducing a novel form of clause abstraction, a core component in the
hierarchic superposition calculus for transforming clauses into a form needed
for internal operation. We argue for the benefits of the resulting calculus and
provide two new completeness results: one for the fragment where all
background-sorted terms are ground and another one for a special case of linear
(integer or rational) arithmetic as a background theory
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