11,151 research outputs found
Quasiequational Theories of Flat Algebras
We prove that finite flat digraph algebras and, more generally, finite compatible flat algebras satisfying a certain condition are finitely q-based (possess a finite basis for their quasiequations). We also exhibit an example of a twelve-element compatible flat algebra that is not finitely q-based
Review of ride quality technology needs of industry and user groups
A broad survey of ride quality technology state-of-the-art and a review of user evaluation of this technology were conducted. During the study 17 users of ride quality technology in 10 organizations representing land, marine and air passenger transportation modes were interviewed. Interim results and conclusions of this effort are reported
User evaluation of ride technology research
The 23 organizations queried represent government, carrier, and manufacturing interests in air, marine, rail, and surface transportation systems. Results indicate a strong need for common terminology and data analysis/reporting techniques. The various types of ride criteria currently in use are discussed, particularly in terms of their respective data base requirements. A plan of action is proposed for fulfilling the ride technology needs identified by this study
A quantum Monte Carlo study on the superconducting Kosterlitz-Thouless transition of the attractive Hubbard model on a triangular lattice
We study the superconducting Kosterlitz-Thouless transition of the attractive
Hubbard model on a two-dimensional triangular lattice using auxiliary field
quantum Monte Carlo method for system sizes up to sites.
Combining three methods to analyze the numerical data, we find, for the
attractive interaction of , that the transition temperature stays almost
constant within the band filling range of , while it is found to
be much lower in the region.Comment: RevTeX 6 page
Mott transition in two-dimensional frustrated compounds
The phase diagrams of isotropic and anisotropic triangular lattices with
local Coulomb interactions are evaluated within cluster dynamical mean field
theory. As a result of partial geometric frustration in the anisotropic
lattice, short range correlations are shown to give rise to reentrant behavior
which is absent in the fully frustrated isotropic limit. The qualitative
features of the phase diagrams including the critical temperatures are in good
agreement with experimental data for the layered organic charge transfer salts
kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl and kappa-(BEDT-TTF)_2Cu_2(CN)_3.Comment: 4 pages, 4 figure
Dynamical properties of a strongly correlated model for quarter-filled layered organic molecular crystals
The dynamical properties of an extended Hubbard model, which is relevant to
quarter-filled layered organic molecular crystals, are analyzed. We have
computed the dynamical charge correlation function, spectral density, and
optical conductivity using Lanczos diagonalization and large-N techniques. As
the ratio of the nearest-neighbour Coulomb repulsion, V, to the hopping
integral, t, increases there is a transition from a metallic phase to a charge
ordered phase. Dynamical properties close to the ordering transition are found
to differ from the ones expected in a conventional metal. Large-N calculations
display an enhancement of spectral weight at low frequencies as the system is
driven closer to the charge ordering transition in agreement with Lanczos
calculations. As V is increased the charge correlation function displays a
plasmon-like mode which, for wavevectors close to (pi,pi), increases in
amplitude and softens as the charge ordering transition is approached. We
propose that inelastic X-ray scattering be used to detect this mode. Large-N
calculations predict superconductivity with dxy symmetry close to the ordering
transition. We find that this is consistent with Lanczos diagonalization
calculations, on lattices of 20 sites, which find that the binding energy of
two holes becomes negative close to the charge ordering transition.Comment: 22 pages, 16 eps figures; caption of Fig. 5 correcte
The variety generated by order algebras
Every ordered set can be considered as an algebra in a natural way. We investigate the variety generated by order algebras. We prove, among other things, that this variety is not finitely based and, although locally finite, it is not contained in any finitely generated variety; we describe the bottom of the lattice of its subvarieties
Use of thermal infrared and colour infrared imagery to detect crop moisture stress
The author has identified the following significant results. In the presence of variable plant cover (primarily percent cover) and variable available water content, the remotely sensed apparent temperatures correlate closely with plant cover and poorly with soil water. To the extent that plant cover is not systematically related to available soil water, available water in the root zone values may not be reliably predicted from the thermal infrared data. On the other hand, if plant cover is uniform and the soil surface is shown in a minor way, the thermal data indicate plant stress and consequently available water in the soil profile
First-principle density-functional calculation of the Raman spectra of BEDT-TTF
We present a first-principles density-functional calculation for the Raman
spectra of a neutral BEDT-TTF molecule. Our results are in excellent agreement
with experimental results. We show that a planar structure is not a stable
state of a neutral BEDT-TTF molecule. We consider three possible conformations
and discuss their relation to disorder in these systems.Comment: 3 pages, 2 figures, submitted to the proceedings of ISCOM 200
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