6,273 research outputs found
Distribution of Microscopic Energy Flux in Equilibrium State
The distribution function P(j) of the microscopic energy flux, j, in
equilibrium state is studied. It is observed that P(j) has a broad peak in
small j regime and a stretched-exponential decay for large j. The peak
structure originates in a potential advection term and energy transfer term
between the particles. The stretched exponential tail comes from the momentum
energy advection term.Comment: 5 pages, 2 figure
Nonequilibrium Microscopic Distribution of Thermal Current in Particle Systems
A nonequilibrium distribution function of microscopic thermal current is
studied by a direct numerical simulation in a thermal conducting steady state
of particle systems. Two characteristic temperatures of the thermal current are
investigated on the basis of the distribution. It is confirmed that the
temperature depends on the current direction; Parallel temperature to the
heat-flux is higher than antiparallel one. The difference between the parallel
temperature and the antiparallel one is proportional to a macroscopic
temperature gradient.Comment: 4 page
Computing Lyapunov spectra with continuous Gram-Schmidt orthonormalization
We present a straightforward and reliable continuous method for computing the
full or a partial Lyapunov spectrum associated with a dynamical system
specified by a set of differential equations. We do this by introducing a
stability parameter beta>0 and augmenting the dynamical system with an
orthonormal k-dimensional frame and a Lyapunov vector such that the frame is
continuously Gram-Schmidt orthonormalized and at most linear growth of the
dynamical variables is involved. We prove that the method is strongly stable
when beta > -lambda_k where lambda_k is the k'th Lyapunov exponent in
descending order and we show through examples how the method is implemented. It
extends many previous results.Comment: 14 pages, 10 PS figures, ioplppt.sty, iopl12.sty, epsfig.sty 44 k
Interminiband Rabi oscillations in biased semiconductor superlattices
Carrier dynamics at energy level anticrossings in biased semiconductor
superlattices, was studied in the time domain by solving the time-dependent
Schroedinger equation. The resonant nature of interminiband Rabi oscillations
has been explicitly demonstrated to arise from interference of intrawell and
Bloch oscillations. We also report a simulation of direct Rabi oscillations
across three minibands, in the high field regime, due to interaction between
three strongly coupled minibands.Comment: 13 pages, 16 figure
Study on Voltage Controller of Self-Excited Induction Generator Using Controlled Shunt Capacitor, SVC Magnetic Energy Recovery Switch
Reactive compensation is required to maintain terminal voltage of induction generator under varying load and speed operation. A new variable shunt capacitor, which is called SVC magnetic energy recovery switch (SVC MERS), is proposed. The operation principle, characteristics of injected current, operating range of reactive compensation of SVC MERS in star and delta configuration were investigated. Application for induction generator voltage controller, which is required leading reactive compensator, is suitable for SVC MERS. Small scale experiments were conducted to verify the proposed system performance to control induction generator voltage in variable load and speed conditions. The advantage of this device is simple control with low switching frequency. Moreover in delta configuration, the SVC MERS current is low means downsizing of heatsink can be achieved. Keywords : Voltage controller, induction generator, reactive compensation, SVC MER
N-tree approximation for the largest Lyapunov exponent of a coupled-map lattice
The N-tree approximation scheme, introduced in the context of random directed
polymers, is here applied to the computation of the maximum Lyapunov exponent
in a coupled map lattice. We discuss both an exact implementation for small
tree-depth and a numerical implementation for larger s. We find that the
phase-transition predicted by the mean field approach shifts towards larger
values of the coupling parameter when the depth is increased. We conjecture
that the transition eventually disappears.Comment: RevTeX, 15 pages,5 figure
Superstructure-induced splitting of Dirac cones in silicene
Atomic scale engineering of two-dimensional materials could create devices
with rich physical and chemical properties. External periodic potentials can
enable the manipulation of the electronic band structures of materials. A
prototypical system is 3x3-silicene/Ag(111), which has substrate-induced
periodic modulations. Recent angle-resolved photoemission spectroscopy
measurements revealed six Dirac cone pairs at the Brillouin zone boundary of
Ag(111), but their origin remains unclear [Proc. Natl. Acad. Sci. USA 113,
14656 (2016)]. We used linear dichroism angle-resolved photoemission
spectroscopy, the tight-binding model, and first-principles calculations to
reveal that these Dirac cones mainly derive from the original cones at the K
(K') points of free-standing silicene. The Dirac cones of free-standing
silicene are split by external periodic potentials that originate from the
substrate-overlayer interaction. Our results not only confirm the origin of the
Dirac cones in the 3x3-silicene/Ag(111) system, but also provide a powerful
route to manipulate the electronic structures of two-dimensional materials.Comment: 6 pages, 3 figure
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