5,672 research outputs found
Separation of variables and the XXZ Gaudin magnet
In this work we generalise previous results connecting (rational) Gaudin
magnet models and classical separation of variables. It is shown that the
connection persists for the case of linear r-matrix algebra which corresponds
to the trigonometric 4x4 r-matrix (of the XXZ type). We comment also on the
corresponding problem for the elliptic (XYZ) r-matrix. A prescription for
obtaining integrable systems associated with multiple poles of an L-operator is
given.Comment: 11 pages, AMS-Te
Does Long-Term Macrophyte Management in Lakes Affect Biotic Richness and Diversity?
We hypothesize that the richness and diversity of the biota
in Lake Moraine (42°50’47”N, 75°31’39”W) in New York have
been negatively impacted by 60 years of macrophyte and algae
management to control Eurasian watermilfoil (
Myriophyllum
spicatum
L.) and associated noxious plants. To test this
hypothesis we compare water quality characteristics, richness
and selected indicators of plant diversity, zooplankton, benthic
macroinvertebrates and fish in Lake Moraine with those in
nearby Hatch Lake (42°50’06”N, 75°40’67”W). The latter is
of similar size and would be expected to have similar biota,
but has not been subjected to management. Measurements of
temperature, pH, oxygen, conductivity, Secchi transparency,
calcium, total phosphorus and nitrites + nitrates are comparable.
Taxa richness and the diversity indices applied to the
aquatic macrophytes are similar in both lakes. (PDF has 8 pages.
Effects of nonlinear aerodynamics and static aeroelasticity on mission performance calculations for a fighter aircraft
During conceptual design studies of advanced aircraft, the usual practice is to use linear theory to calculate the aerodynamic characteristics of candidate rigid (nonflexible) geometric external shapes. Recent developments and improvements in computational methods, especially computational fluid dynamics (CFD), provide significantly improved capability to generate detailed analysis data for the use of all disciplines involved in the evaluation of a proposed aircraft design. A multidisciplinary application of such analysis methods to calculate the effects of nonlinear aerodynamics and static aeroelasticity on the mission performance of a fighter aircraft concept is described. The aircraft configuration selected for study was defined in a previous study using linear aerodynamics and rigid geometry. The results from the previous study are used as a basis of comparison for the data generated herein. Aerodynamic characteristics are calculated using two different nonlinear theories, potential flow and rotational (Euler) flow. The aerodynamic calculations are performed in an iterative procedure with an equivalent plate structural analysis method to obtain lift and drag data for a flexible (nonrigid) aircraft. These static aeroelastic data are then used in calculating the combat and mission performance characteristics of the aircraft
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