7,227 research outputs found
Retail Gasoline Franchise Terminations and Nonrenewals Under Title I of the Petroleum Marketing Practices Act
First order quantum corrections to the classical reflection factor of the sinh-Gordon model
The sinh-Gordon model is restricted to a half-line by boundary conditions
maintaining integrability. A perturbative calculation of the reflection factor
is given to one loop order in the bulk coupling and to first order in the
difference of the two parameters introduced at the boundary, providing a
further verification of Ghoshal's formula. The calculation is consistent with a
conjecture for the general dependence of the reflection factor on the boundary
parameters and the bulk coupling.Comment: 16 pages, 1 figur
Second order quantum corrections to the classical reflection factor of the sinh-Gordon model
The sinh-Gordon model on a half-line with integrable boundary conditions is
considered in low order perturbation theory developed in affine Toda field
theory. The quantum corrections to the classical reflection factor of the model
are studied up to the second order in the difference of the two boundary
parameters and to one loop order in the bulk coupling. It is noticed that the
general form of the second order quantum corrections are consistent with
Ghoshal's formula.Comment: 24 pages and 1 figure. LaTex2
Self-duality in Generalized Lorentz Superspaces
We extend the notion of self-duality to spaces built from a set of
representations of the Lorentz group with bosonic or fermionic behaviour, not
having the traditional spin-one upper-bound of super Minkowski space. The
generalized derivative vector fields on such superspaces are assumed to form a
superalgebra. Introducing corresponding gauge potentials and hence covariant
derivatives and curvatures, we define generalized self-duality as the Lorentz
covariant vanishing of certain irreducible parts of the curvatures.Comment: 6 pages, Late
Measured performance of a tip-controlled, teetered rotor with an NACA 64 sub 3-618 tip airfoil
Tests were conducted on the Mod-O 100 kW Wind Turbine to determine the performance of a tip-controlled rotor having an NACA 64 sub-618 airfoil over the moveable outboard 30% of the blade, while operating at nominal rotor speeds of 21 and 31 rpm. Tests were conducted at two rotor speeds to assess the performance improvement which could be realized with 2-speed operation. Test data are compared with analytical predictions and concluding remarks are presented. The results indicate a clear performance improvement for the 2-speed operation
Results of free yaw tests of the Mod-O 100 kilowatt wind turbine
Tests were conducted on the Mod-O 100 kW experimental wind turbine to provide data on yaw alignment characteristics of a large horizontal axis wind turbine with its yaw restraint removed (i.e., in free yaw). The wind turbine consisted of a downwind horizontal axis rotor mounted on a tubular tower. Three rotor configurations were tested. Each rotor was teetered, coned 3 deg and tip-controlled. Two of the rotors had pitch-flap coupling or Delta-3, and one rotor had none. The two rotors with Delta-3 differed in the airfoil used in the tip sections. Test results indicate the rotor without pitch-flap coupling did not align closer than 25 deg with the wind, and pitch-flap coupling improved the wind turbine's alignment with the wind. Yaw damping was shown to have a favorable effect on free yaw characteristics. The change in the tip airfoil section was shown to affect the free yaw alignment also. The rotors with Delta-3 were shown to be capable of responding to wind shifts and exhibited stable operating properties
Stall induced instability of a teetered rotor
Recent tests on the 38m Mod-0 horizontal experimental wind turbine yielded quantitative information on stall induced instability of a teetered rotor. Tests were conducted on rotor blades with NACA 230 series and NACA 643-618 airfoils at low rotor speeds to produce high angles of attack at relatively low wind speeds and power levels. The behavior of the rotor shows good agreement with predicted rotor response based on blade angle of attack calculations and airfoil section properties. The untwisted blades with the 64 series airfoil sections had a slower rate of onset of rotor instability when compared with the twisted 230 series blades, but high teeter angles and teeter stop impacts were experienced with both rotors as wind speeds increased to produce high angles of attack on the outboard portion of the blade. The relative importance of blade twist and airfoil section stall characteristics on the rate of onset of rotor unstability with increasing wind speed was not established however. Blade pitch was shown to be effective in eliminating rotor instability at the expense of some loss in rotor performance near rated wind speed
Generalised Calogero-Moser models and universal Lax pair operators
Calogero-Moser models can be generalised for all of the finite reflection
groups. These include models based on non-crystallographic root systems, that
is the root systems of the finite reflection groups, H_3, H_4, and the dihedral
group I_2(m), besides the well-known ones based on crystallographic root
systems, namely those associated with Lie algebras. Universal Lax pair
operators for all of the generalised Calogero-Moser models and for any choices
of the potentials are constructed as linear combinations of the reflection
operators. The consistency conditions are reduced to functional equations for
the coefficient functions of the reflection operators in the Lax pair. There
are only four types of such functional equations corresponding to the
two-dimensional sub-root systems, A_2, B_2, G_2, and I_2(m). The root type and
the minimal type Lax pairs, derived in our previous papers, are given as the
simplest representations. The spectral parameter dependence plays an important
role in the Lax pair operators, which bear a strong resemblance to the Dunkl
operators, a powerful tool for solving quantum Calogero-Moser models.Comment: 37 pages, LaTeX2e, no macro, no figur
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The eyes of suckermouth armoured catfish (Loricariidae, subfamily Hypostomus): pupil response, lenticular longitudinal spherical aberration and retinal topography
The dilated, round pupils of a species of suckermouth armoured catfish (Liposarcus pardalis) constrict slowly on illumination (over 35-40 min) to form crescent-shaped apertures. Ray tracing of He-Ne laser beams shows that the lenses of a related species (Pterygoplichthys etentaculus), which also has a crescent-shaped pupil, are well corrected for longitudinal spherical aberration, suggesting that the primary purpose of the irregular pupil in armoured catfish is not to correct such aberration. It is suggested that the iris operculum may serve to camouflage the pupil of these substrate-dwelling species. An examination of the catfish retina shows the photoreceptors to be exclusively single cones interspersed with elongate rods and demonstrates the presence of multiple optic nerve head papillae. Two areas of high ganglion cell density, each side of a vertically oriented falciform process, provide increased spatial resolving power along the axes examining the substrate in front of and behind the animal
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