Subminiature micropower digital recorder

High-density digital data, collected periodically or randomly from multiplicity of sensors, are recorded by subminiature recorder. Magnetic recording head is energized with suitable pulsatile signals to reverse polarization on magnetically-sensitive tape while tape is immobilized at recording head. Prior to next recording, set tape so new area of tape is at recording head

Establishment of Tall Fescue on West Louisiana Coastal Plain Soils (Bulletin #859)

Georgia-5 tall fescue was developed for use as a permanent, cool-season pasture grass on the Coastal Plain. The results of two field plot experiments and observations from additional small-plot plantings and 40 acres of pasture for grazing experiments at the Rosepine Research Station provide the basis for this discussion of Georgia-5 tall fescue establishment.https://digitalcommons.lsu.edu/agcenter_bulletins/1018/thumbnail.jp

Little Phillip No. 1 Bermudagrass (Research Information Sheet #106)

A unique, naturally occurring variety of Bermudagrass was identified in an Alicia Bermudagrass hay field in Sabine Parish in 1991. This publication includes information on the comparisons of this variety with the three Bermudagrass varieties most widely planted in the area in recent years, conducted in a field plot experiment at the Rosepine Research Station.https://digitalcommons.lsu.edu/agcenter_researchinfosheets/1006/thumbnail.jp

Establishing bundleflowers in bermuda and switchgrass

Last updated: 10/22/201

Eigen-analysis of Inviscid Fluid Structure Interaction (FSI) Systems with Complex Boundary Conditions

A method for extracting the eigenvalues and eigenmodes from complex coupled fluid-structure interaction (FSI) systems is presented. The FSI system under consideration in this case is a one-sided, inviscid flow over a finite-length compliant surface with complex boundary conditions, although the method could be applied to any FSI system. The flow is solved for the inviscid case using a boundary-element method solution of Laplace’s equation, while the finite compliant surface is solved through a finite-difference solution of the one-dimensional beam equation. The crux of the method lies in reducing the coupled fluid and structural equations down to a set of coupled linear differential equations. Standard Krylov subspace projection methods may then be used to determine the eigenvalues of the large system of linear equations. This method is applied to the analysis of hydroelastic FSI systems with complex boundary conditions that would be difficult or otherwise impossible to analyse using standard Galerkin methods. Specifically, the complex cases of inhomogeneous and discontinuous compliant wall properties and arbitrary hinge-joint conditions along the compliant surface are considered

Eigen-analysis of a Fully Viscous Boundary-Layer flow Interacting with a Finite Compliant Surface

A method and preliminary results are presented for the determination of eigenvalues and eigenmodes from fully viscous boundary layer flow interacting with a finite length one-sided compliant wall. This is an extension to the analysis of inviscid flow-structure systems which has been established in previous work. A combination of spectral and finite-difference methods are applied to a linear perturbation form of the full Navier-Stokes equations and one-dimensional beam equation. This yields a system of coupled linear equations that accurately define the spatio-temporal development of linear perturbations to a boundary layer flow over a finite-length compliant surface. Standard Krylov subspace projection methods are used to extract the eigenvalues from this complex system of equations. To date, the analysis of the development of Tollmien-Schlichting (TS) instabilities over a finite compliant surface have relied upon DNS-type results across a narrow (or even singular) spectrum of TS waves. The results from this method have the potential to describe conclusively the role that a finite length compliant surface has in the development of two-dimensional TS instabilities and other FSI instabilities across a broad spectrum

Antarctic killer whales make rapid, round-trip movements to subtropical waters: evidence for physiological maintenance migrations?

Killer whales (Orcinus orca) are important predators in high latitudes, where their ecological impact is mediated through their movements. We used satellite telemetry to provide the first evidence of migration for killer whales, characterized by fast (more than 12 km h−1, 6.5 knots) and direct movements away from Antarctic waters by six of 12 type B killer whales tagged when foraging near the Antarctic Peninsula, including all tags transmitting for more than three weeks. Tags on five of these whales revealed consistent movements to subtropical waters (30–37° S) off Uruguay and Brazil, in surface water temperatures ranging from −1.9°C to 24.2°C; one 109 day track documented a non-stop round trip of almost 9400 km (5075 nmi) in just 42 days. Although whales travelled slower in the warmest waters, there was no obvious interruption in swim speed or direction to indicate calving or prolonged feeding. Furthermore, these movements were aseasonal, initiating over 80 days between February and April; one whale returned to within 40 km of the tagging site at the onset of the austral winter in June. We suggest that these movements may represent periodic maintenance migrations, with warmer waters allowing skin regeneration without the high cost of heat loss: a physiological constraint that may also affect other whales

Transport composite fuselage technology: Impact dynamics and acoustic transmission

A program was performed to develop and demonstrate the impact dynamics and acoustic transmission technology for a composite fuselage which meets the design requirements of a 1990 large transport aircraft without substantial weight and cost penalties. The program developed the analytical methodology for the prediction of acoustic transmission behavior of advanced composite stiffened shell structures. The methodology predicted that the interior noise level in a composite fuselage due to turbulent boundary layer will be less than in a comparable aluminum fuselage. The verification of these analyses will be performed by NASA Langley Research Center using a composite fuselage shell fabricated by filament winding. The program also developed analytical methodology for the prediction of the impact dynamics behavior of lower fuselage structure constructed with composite materials. Development tests were performed to demonstrate that the composite structure designed to the same operating load requirement can have at least the same energy absorption capability as aluminum structure

Solution of the Fokker-Planck equation with a logarithmic potential and mixed eigenvalue spectrum

Motivated by a problem in climate dynamics, we investigate the solution of a Bessel-like process with negative constant drift, described by a Fokker-Planck equation with a potential V(x) = - [b \ln(x) + a\, x], for b>0 and a<0. The problem belongs to a family of Fokker-Planck equations with logarithmic potentials closely related to the Bessel process, that has been extensively studied for its applications in physics, biology and finance. The Bessel-like process we consider can be solved by seeking solutions through an expansion into a complete set of eigenfunctions. The associated imaginary-time Schroedinger equation exhibits a mix of discrete and continuous eigenvalue spectra, corresponding to the quantum Coulomb potential describing the bound states of the hydrogen atom. We present a technique to evaluate the normalization factor of the continuous spectrum of eigenfunctions that relies solely upon their asymptotic behavior. We demonstrate the technique by solving the Brownian motion problem and the Bessel process both with a negative constant drift. We conclude with a comparison with other analytical methods and with numerical solutions.Comment: 21 pages, 8 figure