993 research outputs found
Dynamical electron transport through a nanoelectromechanical wire in a magnetic field
We investigate dynamical transport properties of interacting electrons moving
in a vibrating nanoelectromechanical wire in a magnetic field. We have built an
exactly solvable model in which electric current and mechanical oscillation are
treated fully quantum mechanically on an equal footing. Quantum mechanically
fluctuating Aharonov-Bohm phases obtained by the electrons cause nontrivial
contribution to mechanical vibration and electrical conduction of the wire. We
demonstrate our theory by calculating the admittance of the wire which are
influenced by the multiple interplay between the mechanical and the electrical
energy scales, magnetic field strength, and the electron-electron interaction
Anterior Hippocampus and Goal-Directed Spatial Decision Making
Contains fulltext :
115487.pdf (publisher's version ) (Open Access
Application of feedback linearization to tracking and almost disturbance decoupling control of the AMIRA ball and beam system
This paper studies the tracking and almost disturbance decoupling problem of the nonlinear AMIRA ball and beam system based on the feedback linearization approach. The main contribution of this study is to construct a controller, under appropriate conditions, such that the resulting closed-loop system is valid for any initial condition and bounded tracking signal with the following characteristics: input-to-state stability with respect to disturbance inputs and almost disturbance decoupling. Two examples on the almost disturbance decoupling problem, which cannot be solved via Ref. 1, are proposed in this paper exploiting the fact that the tracking and the almost disturbance decoupling performances are easily achieved by our proposed approach
Recent experimental results in sub- and near-barrier heavy ion fusion reactions
Recent advances obtained in the field of near and sub-barrier heavy-ion
fusion reactions are reviewed. Emphasis is given to the results obtained in the
last decade, and focus will be mainly on the experimental work performed
concerning the influence of transfer channels on fusion cross sections and the
hindrance phenomenon far below the barrier. Indeed, early data of sub-barrier
fusion taught us that cross sections may strongly depend on the low-energy
collective modes of the colliding nuclei, and, possibly, on couplings to
transfer channels. The coupled-channels (CC) model has been quite successful in
the interpretation of the experimental evidences. Fusion barrier distributions
often yield the fingerprint of the relevant coupled channels. Recent results
obtained by using radioactive beams are reported. At deep sub-barrier energies,
the slope of the excitation function in a semi-logarithmic plot keeps
increasing in many cases and standard CC calculations over-predict the cross
sections. This was named a hindrance phenomenon, and its physical origin is
still a matter of debate. Recent theoretical developments suggest that this
effect, at least partially, may be a consequence of the Pauli exclusion
principle. The hindrance may have far-reaching consequences in astrophysics
where fusion of light systems determines stellar evolution during the carbon
and oxygen burning stages, and yields important information for exotic
reactions that take place in the inner crust of accreting neutron stars.Comment: 40 pages, 63 figures, review paper accepted for EPJ
Hamiltonian Formalism of the de-Sitter Invariant Special Relativity
Lagrangian of the Einstein's special relativity with universal parameter
() is invariant under Poincar\'e transformation which preserves
Lorentz metric . The has been extended to be
one which is invariant under de Sitter transformation that preserves so called
Beltrami metric . There are two universal parameters and in
this Special Relativity (denote it as ). The
Lagrangian-Hamiltonian formulism of is formulated in this
paper. The canonic energy, canonic momenta, and 10 Noether charges
corresponding to the space-time's de Sitter symmetry are derived. The canonical
quantization of the mechanics for -free particle is
performed. The physics related to it is discussed.Comment: 24 pages, no figur
Interacting Agegraphic Dark Energy
A new dark energy model, named "agegraphic dark energy", has been proposed
recently, based on the so-called K\'{a}rolyh\'{a}zy uncertainty relation, which
arises from quantum mechanics together with general relativity. In this note,
we extend the original agegraphic dark energy model by including the
interaction between agegraphic dark energy and pressureless (dark) matter. In
the interacting agegraphic dark energy model, there are many interesting
features different from the original agegraphic dark energy model and
holographic dark energy model. The similarity and difference between agegraphic
dark energy and holographic dark energy are also discussed.Comment: 10 pages, 5 figures, revtex4; v2: references added; v3: accepted by
Eur. Phys. J. C; v4: published versio
Underlying Pairing States in Cuprate Superconductors
In this Letter, we develop a microscopic theory to describe the close
proximity between the insulating antiferromagnetic (AF) order and the d-wave
superconducting (dSC) order in cuprates. We show that the cuprate ground states
form a configuration of coherent pairing states consisting of extended singlet
Cooper pairs and triplet pairs, which can simultaneously describe AF and
dSC orders.Comment: 4 papes, 1 figur
Crossing w=-1 in Gauss-Bonnet Brane World with Induced Gravity
Recent type Ia supernovas data seemingly favor a dark energy model whose
equation of state crosses -1 very recently, which is a much more amazing
problem than the acceleration of the universe. In this paper we show that it is
possible to realize such a crossing without introducing any phantom component
in a Gauss-Bonnet brane world with induced gravity, where a four dimensional
curvature scalar on the brane and a five dimensional Gauss-Bonnet term in the
bulk are present. In this realization, the Gauss-Bonnet term and the mass
parameter in the bulk play a crucial role.Comment: Revtex 16 pages including 10 eps files, references added, to appear
in Comm. Theor. Phy
Fatal Void Size Comparisons in Via-Below and Via-Above Cu Dual-Damascene Interconnects
The median-times-to-failure (t₅₀’s) for straight dual-damascene via-terminated copper interconnect structures, tested under the same conditions, depend on whether the vias connect down to underlaying leads (metal 2, M2, or via-below structures) or connect up to overlaying leads (metal 1, M1, or via-above structures). Experimental results for a variety of line lengths, widths, and numbers of vias show higher t₅₀’s for M2 structures than for analogous M1 structures. It has been shown that despite this asymmetry in lifetimes, the electromigration drift velocity is the same for these two types of structures, suggesting that fatal void volumes are different in these two cases. A numerical simulation tool based on the Korhonen model has been developed and used to simulate the conditions for void growth and correlate fatal void sizes with lifetimes. These simulations suggest that the average fatal void size for M2 structures is more than twice the size of that of M1 structures. This result supports an earlier suggestion that preferential nucleation at the Cu/Si₃N₄ interface in both M1 and M2 structures leads to different fatal void sizes, because larger voids are required to span the line thickness in M2 structures while smaller voids at the base of vias can cause failures in M1 structures. However, it is also found that the fatal void sizes corresponding to the shortest-times-to-failure (STTF’s) are similar for M1 and M2, suggesting that the voids that lead to the shortest lifetimes occur at or in the vias in both cases, where a void need only span the via to cause failure. Correlation of lifetimes and critical void volumes provides a useful tool for distinguishing failure mechanisms.Singapore-MIT Alliance (SMA
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