410 research outputs found
The exact evaluation of the corner-to-corner resistance of an M x N resistor network: Asymptotic expansion
We study the corner-to-corner resistance of an M x N resistor network with
resistors r and s in the two spatial directions, and obtain an asymptotic
expansion of its exact expression for large M and N. For M = N, r = s =1, our
result is
R_{NxN} = (4/pi) log N + 0.077318 + 0.266070/N^2 - 0.534779/N^4 + O(1/N^6).Comment: 12 pages, re-arranged section
Nonlinear and spin-glass susceptibilities of three site-diluted systems
The nonlinear magnetic and spin-glass susceptibilities
in zero applied field are obtained, from tempered Monte Carlo simulations, for
three different spin glasses (SGs) of Ising spins with quenched site disorder.
We find that the relation ( is the temperature),
which holds for Edwards-Anderson SGs, is approximately fulfilled in
canonical-like SGs. For nearest neighbor antiferromagnetic interactions, on a
0.4 fraction of all sites in fcc lattices, as well as for spatially disordered
Ising dipolar (DID) systems, and appear to diverge in
the same manner at the critical temperature . However, is
smaller than by over two orders of magnitude in the diluted fcc
system. In DID systems, is very sensitive to the systems
aspect ratio. Whereas near , varies by approximately a
factor of 2 as system shape varies from cubic to long-thin-needle shapes,
sweeps over some four decades.Comment: 7 pages, 7 figure
Low-density series expansions for directed percolation III. Some two-dimensional lattices
We use very efficient algorithms to calculate low-density series for bond and
site percolation on the directed triangular, honeycomb, kagom\'e, and
lattices. Analysis of the series yields accurate estimates of the critical
point and various critical exponents. The exponent estimates differ only
in the digit, thus providing strong numerical evidence for the
expected universality of the critical exponents for directed percolation
problems. In addition we also study the non-physical singularities of the
series.Comment: 20 pages, 8 figure
ENHANCEMENT OF LORNOXICAM SOLUBILITY BY INCLUSION COMPLEXATION WITH CYCLODEXTRIN: PREPARATION AND CHARACTERIZATION
Objective: Lornoxicam is a potent anti-inflammatory drug which has analgesic and antipyretic properties. It is water-insoluble powder. The inclusion complexes of lornoxicam (LOR) with β-cyclodextrin (βCD) and 2-hydroxypropyl-β-cyclodextrin (HPCD) were prepared and characterised in order to improve the solubility of the drug and enhance its bioavailability.Methods: Complexes were prepared by physical mixing and freeze-drying in three different drug/polymer ratios (1:1, 1:2 and 3:2). The solid complexes were characterised through differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, and Fourier transformed infrared (FTIR) spectroscopy.Results: The data showed that LOR may be complexed with cyclodextrin (CD) forming soluble complexes. The lyophilized 1:2 LOR/HPCD complex is the most soluble.Conclusion: Solubility increases with lyophilization than with physical mixing and by the use of HPCD than βCD in complexation
Aerostructural Vortical Flow Interactions with Applications to F/A-18 and F-117 Tail Buffet
The buffet response of the flexible twin-tail configuration of the F/A-18 and a generic F-111 aircraft are computationally simulated and experimentally validated. The problem is a multidisciplinary one which requires the sequential solution of three sets of equations on a multi-block grid structure. The first set is the unsteady, compressible, full Navier-Stokes equations. The second set is the aeroelastic equations for bending and torsional twin-tail responses. The third set is the grid-displacement equations which are used to update the grid coordinates due to the tail deflections. The computational models consist of a 76 deg. swept back, sharp edged delta wing of aspect ratio of one and a swept-back F/A-18 or F-117 twin-tail. The configuration is pitched at 30 deg. angle-of-attack. The problem is solved for the initial flow conditions with the twin tails kept rigid. Next, the aeroelastic equations of the tails are turned on along with the grid-displacement equations to solve for the bending and torsional tails responses due to the unsteady loads produced by the vortex breakdown flow of the leading-edge vortex cores of the delta wing. Several spanwise locations of the twin tails are investigated. The computational results are validated using several existing experimental data
Branching Transition of a Directed Polymer in Random Medium
A directed polymer is allowed to branch, with configurations determined by
global energy optimization and disorder. A finite size scaling analysis in 2D
shows that, if disorder makes branching more and more favorable, a critical
transition occurs from the linear scaling regime first studied by Huse and
Henley [Phys. Rev. Lett. 54, 2708 (1985)] to a fully branched, compact one. At
criticality clear evidence is obtained that the polymer branches at all scales
with dimension and roughness exponent satisfying , and energy fluctuation exponent , in terms of longitudinal distanceComment: REVTEX, 4 pages, 3 encapsulated eps figure
New order parameters in the Potts model on a Cayley tree
For the state Potts model new order parameters projecting on a group of
spins instead of a single spin are introduced. On a Cayley tree this allows the
physical interpretation of the Potts model at noninteger values q of the number
of states. The model can be solved recursively. This recursion exhibits chaotic
behaviour changing qualitatively at critical values of . Using an
additional order parameter belonging to a group of zero extrapolated size the
additional ordering is related to a percolation problem. This percolation
distinguishes different phases and explains the critical indices of percolation
class occuring at the Peierls temperature.Comment: 16 pages TeX, 5 figures PostScrip
- …