6,714 research outputs found
Solve scheduling problems with a fuzzy approach
Scheduling is a complex problem which occurs often in a manufacturing environment. Most of the available schedulers are based on a simulation approach using dispatching rules. These rules are often dedicated to the satisfaction of a single performance criterion, and are used whatever the characteristics of the system or the type of jobs, though scheduling is a multi-criteria problem. In this paper the scheduling problems are addressed using a non-classical approach supported by fuzzy control theory. The ability to deal with multi-variables makes fuzzy control a good alternative for the scheduling problems because it can easily make compromises among multi-criteria by properly combining elementary dispatching rules. These compromises can easily be adjusted in accordance with the objectives of the system and the characteristics of the jobs. The proposed method has been implemented and tested in a discrete event simulation environment. The results are presented in this pape
Optimal quantum pump in the presence of a superconducting lead
We investigate the parametric pumping of a hybrid structure consisting of a
normal quantum dot, a normal lead and a superconducting lead. Using the time
dependent scattering matrix theory, we have derived a general expression for
the pumped electric current and heat current. We have also derived the
relationship among the instantaneous pumped heat current, electric current, and
shot noise. This gives a lower bound for the pumped heat current in the hybrid
system similar to that of the normal case obtained by Avron et al
Signature of Spin Collective Mode in Local Tunneling Spectra of a d-wave Superconductor
We consider the influence of magnetic excitations on the local density of
states in the d-wave superconductor. The magnetic susceptibility is calculated
within the renormalized model and its influence on the quasiparticle
self-energy is considered using a minimal model originally proposed by
Polkovnikov {\it et al.}[cond-mat/0203176]. We find the local density of states
possess periodic components both along and directions
with the associated wavevectors changing in magnitude as the quasiparticle
energy is varied. Comparison with the STM experiment reveals that the
calculated LDOS modulation is inconsistent with the measured data.Comment: Two figures separately attached as .jpg file
Scattering Theory of Dynamic Electrical Transport
We have developed a scattering matrix approach to coherent transport through
an adiabatically driven conductor based on photon-assisted processes. To
describe the energy exchange with the pumping fields we expand the Floquet
scattering matrix up to linear order in driving frequency.Comment: Proceedings QMath9, September 12th-16th, 2004, Giens, Franc
Defect and anisotropic gap induced quasi-one-dimensional modulation of local density of states in YBaCuO
Motivated by recent angle-resolved photoemission spectroscopy (ARPES)
measurement that superconducting YBaCuO (YBCO) exhibits a
-symmetry gap, we show possible quasi-one-dimensional
modulations of local density of states in YBCO. These aniostropic gap and
defect induced stripe structures are most conspicuous at higher biases and
arise due to the nesting effect associated with a Fermi liquid. Observation of
these spectra by scanning tunneling microscopy (STM) would unify the picture
among STM, ARPES, and inelastic neutron scattering for YBCO.Comment: 4 pages, 4 figure
Observations of Alcator C-MOD plasmas from a 5 chord high energy resolution x-ray spectrometer array
Undecidable properties of self-affine sets and multi-tape automata
We study the decidability of the topological properties of some objects
coming from fractal geometry. We prove that having empty interior is
undecidable for the sets defined by two-dimensional graph-directed iterated
function systems. These results are obtained by studying a particular class of
self-affine sets associated with multi-tape automata. We first establish the
undecidability of some language-theoretical properties of such automata, which
then translate into undecidability results about their associated self-affine
sets.Comment: 10 pages, v2 includes some corrections to match the published versio
Stress-modulated relaxor-to-ferroelectric transition in lead-free (N a1/2 B i1/2)Ti O₃-BaTi O₃ ferroelectrics
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