5,949 research outputs found
Exclusive Operation Strategy for the Supervisory Control of Series Hybrid Electric Vehicles
Supervisory control systems (SCSs) are used to manage the powertrain of hybrid electric vehicles (HEV). This paper presents a novel SCS called Exclusive operation strategy (XOS) that applies simple rules based on the idea that batteries are efficient at lower loads while engines and generators are efficient at higher loads. The XOS is developed based on insights gained from three conventional SCSs for series HEVs: Thermostat control strategy (TCS), Power follower control strategy (PFCS) and Global equivalent consumption minimization strategy (GECMS). Also, recent technological developments have been considered to make the XOS more suited to modern HEVs than conventional SCSs. The resulting control decisions are shown to emulate the operation of approximate global optimal solutions and thus achieve significant improvement in fuel economy as compared to TCS and PFCS. In addition, the generally linear relationship between required power and engine power for the XOS provides auditory cues to the driver that are comparable to conventional vehicles, thus reducing barriers to adopting HEVs. The simplicity and effectiveness of the XOS makes it a practical SCS
Critical Quantum Chaos in 2D Disordered Systems with Spin-Orbit Coupling
We examine the validity of the recently proposed semi-Poisson level spacing
distribution function P(S), which characterizes `critical quantum chaos', in 2D
disordered systems with spin-orbit coupling. At the Anderson transition we show
that the semi-Poisson P(S) can describe closely the critical distribution
obtained with averaged boundary conditions, over Dirichlet in one direction
with periodic in the other and Dirichlet in both directions. We also obtain a
sub-Poisson linear number variance ,
with asymptotic value . The obtained critical statistics,
intermediate between Wigner and Poisson, is relevant for disordered systems and
chaotic models.Comment: 4 pages with 5 figure
Environment-Mediated Quantum State Transfer
We propose a scheme for quantum state transfer(QST) between two qubits which
is based on their individual interaction with a common boson environment. The
corresponding single mode spin-boson Hamiltonian is solved by mapping it onto a
wave propagation problem in a semi-infinite ladder and the fidelity is
obtained. High fidelity occurs when the qubits are equally coupled to the boson
while the fidelity becomes smaller for nonsymmetric couplings. The complete
phase diagram for such an arbitrary QST mediated by bosons is discussed.Comment: 6 pages and 5 figure
Superconductivity-Induced Anderson Localisation
We have studied the effect of a random superconducting order parameter on the
localization of quasi-particles, by numerical finite size scaling of the
Bogoliubov-de Gennes tight-binding Hamiltonian. Anderson localization is
obtained in d=2 and a mobility edge where the states localize is observed in
d=3. The critical behavior and localization exponent are universal within error
bars both for real and complex random order parameter. Experimentally these
results imply a suppression of the electronic contribution to thermal transport
from states above the bulk energy gap.Comment: 4 pages, revtex file, 3 postscript figure
Multifractal properties of critical eigenstates in two-dimensional systems with symplectic symmetry
The multifractal properties of electronic eigenstates at the metal-insulator
transition of a two-dimensional disordered tight-binding model with spin-orbit
interaction are investigated numerically. The correlation dimensions of the
spectral measure and of the fractal eigenstate are
calculated and shown to be related by . The exponent
describing the energy correlations of the critical
eigenstates is found to satisfy the relation .Comment: 6 pages RevTeX; 3 uuencoded, gzipped ps-figures to appear in J. Phys.
Condensed Matte
- …