228,269 research outputs found

### Some Recent Results on Pair Correlation Functions and Susceptibilities in Exactly Solvable Models

Using detailed exact results on pair-correlation functions of Z-invariant
Ising models, we can write and run algorithms of polynomial complexity to
obtain wavevector-dependent susceptibilities for a variety of Ising systems.
Reviewing recent work we compare various periodic and quasiperiodic models,
where the couplings and/or the lattice may be aperiodic, and where the Ising
couplings may be either ferromagnetic, or antiferromagnetic, or of mixed sign.
We present some of our results on the square-lattice fully-frustrated Ising
model. Finally, we make a few remarks on our recent works on the pentagrid
Ising model and on overlapping unit cells in three dimensions and how these
works can be utilized once more detailed results for pair correlations in,
e.g., the eight-vertex model or the chiral Potts model or even
three-dimensional Yang-Baxter integrable models become available.Comment: LaTeX2e using iopart.cls, 10 pages, 5 figures (5 eps files), Dunk
Island conference in honor of 60th birthday of A.J. Guttman

### Correlation functions for the three state superintegrable chiral Potts spin chain of finite lengths

We compute the correlation functions of the three state superintegrable
chiral Potts spin chain for chains of length 3,4,5. From these results we
present conjectures for the form of the nearest neighbor correlation function.Comment: 10 pages; references update

### Quantum Loop Subalgebra and Eigenvectors of the Superintegrable Chiral Potts Transfer Matrices

It has been shown in earlier works that for Q=0 and L a multiple of N, the
ground state sector eigenspace of the superintegrable tau_2(t_q) model is
highly degenerate and is generated by a quantum loop algebra L(sl_2).
Furthermore, this loop algebra can be decomposed into r=(N-1)L/N simple sl_2
algebras. For Q not equal 0, we shall show here that the corresponding
eigenspace of tau_2(t_q) is still highly degenerate, but splits into two
spaces, each containing 2^{r-1} independent eigenvectors. The generators for
the sl_2 subalgebras, and also for the quantum loop subalgebra, are given
generalizing those in the Q=0 case. However, the Serre relations for the
generators of the loop subalgebra are only proven for some states, tested on
small systems and conjectured otherwise. Assuming their validity we construct
the eigenvectors of the Q not equal 0 ground state sectors for the transfer
matrix of the superintegrable chiral Potts model.Comment: LaTeX 2E document, using iopart.cls with iopams packages. 28 pages,
uses eufb10 and eurm10 fonts. Typeset twice! Version 2: Details added,
improvements and minor corrections made, erratum to paper 2 included. Version
3: Small paragraph added in introductio

### Micro-electroforming metallic bipolar electrodes for mini-DMFC stacks

This paper describes the development of metallic bipolar plate fabrication
using micro-electroforming process for mini-DMFC (direct methanol fuel cell)
stacks. Ultraviolet (UV) lithography was used to define micro-fluidic channels
using a photomask and exposure process. Micro-fluidic channels mold with 300
micrometers thick and 500 micrometers wide were firstly fabricated in a
negative photoresist onto a stainless steel plate. Copper micro-electroforming
was used to replicate the micro-fluidic channels mold. Following by sputtering
silver (Ag) with 1.2 micrometers thick, the metallic bipolar plates were
completed. The silver layer is used for corrosive resistance. The completed
mini-DMFC stack is a 2x2 cm2 fuel cell stack including a 1.5x1.5 cm2 MEA
(membrane electrode assembly). Several MEAs were assembly into mini-DMFC stacks
using the completed metallic bipolar plates. All test results showed the
metallic bipolar plates suitable for mini-DMFC stacks. The maximum output power
density is 9.3mW/cm2 and current density is 100 mA/cm2 when using 8 vol. %
methanol as fuel and operated at temperature 30 degrees C. The output power
result is similar to other reports by using conventional graphite bipolar
plates. However, conventional graphite bipolar plates have certain difficulty
to be machined to such micro-fluidic channels. The proposed
micro-electroforming metallic bipolar plates are feasible to miniaturize DMFC
stacks for further portable 3C applications.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838

### Solitary Waves Bifurcated from Bloch Band Edges in Two-dimensional Periodic Media

Solitary waves bifurcated from edges of Bloch bands in two-dimensional
periodic media are determined both analytically and numerically in the context
of a two-dimensional nonlinear Schr\"odinger equation with a periodic
potential. Using multi-scale perturbation methods, envelope equations of
solitary waves near Bloch bands are analytically derived. These envelope
equations reveal that solitary waves can bifurcate from edges of Bloch bands
under either focusing or defocusing nonlinearity, depending on the signs of
second-order dispersion coefficients at the edge points. Interestingly, at edge
points with two linearly independent Bloch modes, the envelope equations lead
to a host of solitary wave structures including reduced-symmetry solitons,
dipole-array solitons, vortex-cell solitons, and so on -- many of which have
never been reported before. It is also shown analytically that the centers of
envelope solutions can only be positioned at four possible locations at or
between potential peaks. Numerically, families of these solitary waves are
directly computed both near and far away from band edges. Near the band edges,
the numerical solutions spread over many lattice sites, and they fully agree
with the analytical solutions obtained from envelope equations. Far away from
the band edges, solitary waves are strongly localized with intensity and phase
profiles characteristic of individual families.Comment: 23 pages, 15 figures. To appear in Phys. Rev.

### Towards A Background Independent Quantum Gravity

We recapitulate the scheme of emergent gravity to highlight how a background
independent quantum gravity can be defined by quantizing spacetime itself.Comment: 25 pages, 2 figures, Proceedings of 7th International Conference
"Quantum Theory and Symmetries" (QTS-7) in Prague, Czech Republic, August,
201

### Control of fast electron propagation in foam target by high-Z doping

The influence of high-Z dopant (Bromine) in low-Z foam (polystyrene) target
on laser-driven fast electron propagation is studied by the 3D hybrid
particle-in-cell (PIC)/fluid code HEETS.It is found that the fast electrons are
better confined in doped targets due to the increasing resistivity of the
target, which induces a stronger resistive magnetic field which acts to
collimate the fast electron propagation.The energy deposition of fast electrons
into the background target is increased slightly in the doped target, which is
beneficial for applications requiring long distance propagation of fast
electrons, such as fast ignition

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