Studies of some unconventional systems for solving various landing problems

Solutions to various landing problems were obtained through unconventional systems. The first, of these is the air cushion landing system, where efforts were concentrated on development of adequate braking and steering systems and an improved understanding of scaling laws and behavior. The second was concentrated on use of a wire brush skid as a drag producing device, which was shown to have good friction coefficients and reasonable wear rates at ground bearing pressures up to 689 kPa and forward speeds up to 80 km/hr. The third showed great promise in an active control landing gear where significant load reductions were possible during landing impact and subsequent rollout

Strain-activated structural anisotropy in BaFe2As2

High-resolution single crystal neutron diffraction measurements are presented probing the magnetostructural response to uniaxial pressure in the iron pnictide parent system BaFe2As2. Scattering data reveal a strain-activated, anisotropic broadening of nuclear Bragg reflections, which increases upon cooling below the resolvable onset of global orthorhombicity. This anisotropy in lattice coherence continues to diverge until a lower temperature scale---the first-order onset of antiferromagnetism---is reached. Our data suggest that antiferromagnetism and strong magnetoelastic coupling drive the strain-activated lattice response in this material and that the development of anisotropic lattice coherence under strain is the physical origin for the anomalous nematic anisotropy in this compound.Comment: 5 pages, 4 figure

A Markov Chain based method for generating long-range dependence

This paper describes a model for generating time series which exhibit the statistical phenomenon known as long-range dependence (LRD). A Markov Modulated Process based upon an infinite Markov chain is described. The work described is motivated by applications in telecommunications where LRD is a known property of time-series measured on the internet. The process can generate a time series exhibiting LRD with known parameters and is particularly suitable for modelling internet traffic since the time series is in terms of ones and zeros which can be interpreted as data packets and inter-packet gaps. The method is extremely simple computationally and analytically and could prove more tractable than other methods described in the literatureComment: 8 pages, 2 figure

FERAL HOGS IN THE ROLLING PLAINS OF TEXAS: PERSPECTIVES, PROBLEMS, AND POTENTIAL

Feral hogs (Sus scrofa) have expanded their territory in Texas and are now found in all but the extreme western portions of the state. Perhaps the most dramatic expansion has occurred in the Rolling Plains of northwest Texas. Perspectives on feral hogs range from definitely for to adamantly against. Problems encountered with feral hogs include: (1) damage to crops and livestock, or facilities and equipment, (2) transmission of disease to humans and livestock, or (3) interaction with native wildlife including competition for available resources, depredation and destruction of habitat. The feral hog is also an animal with economic potential. Revenue can be generated by selling or hunting them. Is the feral hog an ecological unknown, an economic liability, or an under-utilized asset? The answer remains to be determined and may depend upon one\u27s individual perspective

Anisotropic Neutron Spin Resonance in Superconducting BaFe1.9_{1.9}Ni0.1_{0.1}As2_2

We use polarized inelastic neutron scattering to show that the neutron spin resonance below $T_c$ in superconducting BaFe$_{1.9}$Ni$_{0.1}$As$_2$ ($T_c=20$ K) is purely magnetic in origin. Our analysis further reveals that the resonance peak near 7~meV only occurs for the planar response. This challenges the common perception that the spin resonance in the pnictides is an isotropic triplet excited state of the singlet Cooper pairs, as our results imply that only the $S_{001}=\pm1$ components of the triplet are involved

Enhancements in Mass Transfer for Carbon Capture Solvents Part I: Homogeneous Catalyst

The novel small molecule carbonic anhydrase (CA) mimic [CoIII(Salphen-COO−)Cl]HNEt3 (1), was synthesized as an additive for increasing CO2 absorption rates in amine-based post-combustion carbon capture processes (CCS), and its efficacy was verified. 1 was designed for use in a kinetically slow but thermally stable blended solvent, containing the primary amines 1-amino-2-propanol (A2P) and 2-amino-2-methyl-1-propanol (AMP). Together, the A2P/AMP solvent and 1 reduce the overall energy penalty associated with CO2 capture from coal-derived flue gas, relative to the baseline solvent MEA. 1 is also effective at increasing absorption kinetics of kinetically fast solvents, such as MEA, which can reduce capital costs by requiring a smaller absorber tower. The transition from catalyst testing under idealized laboratory conditions, to process relevant lab- and bench-scale testing adds many additional variables that are not well understood and rarely discussed. The stepwise testing of both 1 and the novel A2P/AMP solvent blend is described through a transition process that identifies many of these process and evaluation challenges not often addressed when designing a chemical or catalytic additive for industrial CCS systems, where consideration of solvent chemistry is typically the primary goal

The VAST Survey - I. Companions and the unexpected X-ray detection of B6-A7 stars

With an adaptive optics imaging survey of 148 B6-A7 stars, we have tested the hypothesis that unresolved lower-mass companions are the source of the unexpected X-ray detections of stars in this spectral type range. The sample is composed of 63 stars detected in X-rays within the ROSAT All-Sky Survey and 85 stars that form a control sample; both subsets have the same restricted distribution of spectral type, age, X-ray sensitivity and separation coverage. A total of 68 companion candidates are resolved with separations ranging from 0.3" to 26.2", with 23 new detections. The multiple star frequency of the X-ray sample based on companions resolved within the ROSAT error ellipse is found to be 43 (+6,-6)%. The corresponding control sample multiple star frequency is three times lower at 12 (+4,-3)% -- a difference of 31\pm7%. These results are presented in the first of a series of papers based on our Volume-limited A-Star (VAST) survey -- a comprehensive study of the multiplicity of A-type stars.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Societ