F-18 high alpha research vehicle surface pressures: Initial in-flight results and correlation with flow visualization and wind-tunnel data

Pressure distributions measured on the forebody and the leading-edge extensions (LEX's) of the NASA F-18 high alpha research vehicle (HARV) were reported at 10 and 50 degree angles of attack and at Mach 0.20 to 0.60. The results were correlated with HARV flow visualization and 6-percent scale F-18 wind-tunnel-model test results. The general trend in the data from the forebody was for the maximum suction pressure peaks to first appear at an angle of attack (alpha) of approximately 19 degrees and increase in magnitude with angle of attack. The LEX pressure distribution general trend was the inward progression and increase in magnitude of the maximum suction peaks up to vortex core breakdown and then the decrease and general flattening of the pressure distribution beyond that. No significant effect of Mach number was noted for the forebody results. However, a substantial compressibility effect on the LEX's resulted in a significant reduction in vortex-induced suction pressure as Mach number increased. The forebody primary and the LEX secondary vortex separation lines, from surface flow visualization, correlated well with the end of pressure recovery, leeward and windward, respectively, of maximum suction pressure peaks. The flight to wind-tunnel correlations were generally good with some exceptions

Surface flow visualization of separated flows on the forebody of an F-18 aircraft and wind-tunnel model

A method of in-flight surface flow visualization similar to wind-tunnel-model oil flows is described for cases where photo-chase planes or onboard photography are not practical. This method, used on an F-18 aircraft in flight at high angles of attack, clearly showed surface flow streamlines in the fuselage forebody. Vortex separation and reattachment lines were identified with this method and documented using postflight photography. Surface flow angles measured at the 90 and 270 degrees meridians show excellent agreement with the wind tunnel data for a pointed tangent ogive with an aspect ratio of 3.5. The separation and reattachment line locations were qualitatively similar to the F-18 wind-tunnel-model oil flows but neither the laminar separation bubble nor the boundary-layer transition on the wind tunnel model were evident in the flight surface flows. The separation and reattachment line locations were in fair agreement with the wind tunnel data for the 3.5 ogive. The elliptical forebody shape of the F-18 caused the primary separation lines to move toward the leeward meridian. Little effect of angle of attack on the separation locations was noted for the range reported

Time-varying Bayesian Network Meta-Analysis

The presence of methicillin-resistant \textit{Staphylococus Aureus} (MRSA) in complicated skin and soft structure infections (cSSSI) is associated with greater health risks and economic costs to patients. There is concern that MRSA is becoming resistant to other "gold standard" treatments such as vancomycin, and there is disagreement about the relative efficacy of vancocymin compared to linezolid. There are several review papers employing Bayesian Network Meta-Analyses (BNMAs) to investigate which treatments are best for MRSA related cSSSIs, but none address time-based design inconsistencies. This paper proposes a time-varying BNMA (tBNMA), which models time-varying treatment effects across studies using a Gaussian Process kernel. A dataset is compiled from nine existing MRSA cSSSI NMA review papers containing 58 studies comparing 19 treatments over 19 years. tBNMA finds evidence of a non-linear trend in the treatment effect of vancomycin - it became less effective than linezolid between 2002 and 2007, but has since recovered statistical equivalence

The effect of alkalisation on the mechanical properties of natural fibres

A study on the effect of alkalisaton using 3% NaOH solution was carried out on Flax, Kenaf, Abaca and Sisal to observe the impact that the common pre-treatment process has on fibre mechanical properties. The result of the investigation indicated that over-treatment of natural fibres using NaOH could have a negative effect on the base fibre properties. It is concluded that a treatment time of less than 10 minutes is sufficient to remove hemicelluloses and to give the optimum effect

Vacuum infusion of natural fibre composites for structural applications

Numerous methods of manufacturing natural fibre composites have been reported in the literature, including compression moudling, often in conjunction with a hot press. Other forms of composite manufacture include 'Vacuum Assisted Resin Transfer Moulding' (VATRM) and the 'Seemann Composite Resin Infusion Moulding Process' (SCRIMP). These methods have been reported to produce natural fibre composies with reasonable mechanical properties [1-2]. In this paper, a vacuum infusion rig is described that has been developed to produce consistent quality composite plates for studies into optimising natural fibre composites. The process aims to harness the benefits of vacuum infusion and compression moulding, where vacuum infusion encourages the removal of trapped air in the system and hence avoid reduction, and additional compression moulding can help to achieve high volume fractions that are otherwise difficult in other processes

Mechanical testing of natural fibre reinforced polyester resin composites and Mode 1 fracture toughness testing of resin blocks

Recent European Parliament directive requires companies to achieve materials recycling greater than 80% in particular in the automotive sector [1]. The research on natural fibre based composite materials fits well into this ecological image. The advantages of natural fibres over synthetic materials include, low density, relative cheapness, availability and biodegradability. In this paper we explore the fabrication and mechanical testing of natural fibre composites and this is part of an on going study at Strathclyde University and describes the fabrication of composites using natural fibre and styrene polyester resin. The properties of the synthetic resin can be varied by changing the catalysts concentration and flexural (three point bending) and single-edged notched bending (SENB) properties are reported at different concentrations of the catalyst

Carbon-13 in groundwater from English and Norwegian crystalline rock aquifers: a tool for deducing the origin of alkalinity?

The 13C signature is evaluated for various environmental compartments (vegetation, soils, soil gas, rock and groundwater) for three crystalline rock terrains in England and Norway. The data are used to evaluate the extent to which stable carbon isotopic data can be applied to deduce whether the alkalinity in crystalline bedrock groundwaters has its origin in hydrolysis of carbonate or silicate minerals by CO2. The resolution of this issue has profound implications for the role of weathering of crystalline rocks as a global sink for CO2. In the investigated English terrain (Isles of Scilly), groundwaters are hydrochemically immature and DIC is predominantly in the form of carbonic acid with a soil gas signature. In the Norwegian terrains, the evidence is not conclusive but is consistent with a significant fraction of the groundwater DIC being derived from silicate hydrolysis by CO2. A combined consideration of pH, alkalinity and carbon isotope data, plotted alongside theoretical evolutionary pathways on bivariate diagrams, strongly suggests real evolutionary pathways are likely to be hybrid, potentially involving both open and closed CO2 conditions

Reduced dimensionality spin-orbit dynamics of CH3 + HCl reversible arrow CH4 Cl on ab initio surfaces

A reduced dimensionality quantum scattering method is extended to the study of spin-orbit nonadiabatic transitions in the CH3 + HCl reversible arrow CH4 + Cl(P-2(J)) reaction. Three two-dimensional potential energy surfaces are developed by fitting a 29 parameter double-Morse function to CCSD(T)/IB//MP2/cc-pV(T+d)Z-dk ab initio data; interaction between surfaces is described by geometry-dependent spin-orbit coupling functions fit to MCSCF/cc-pV(T+d)Z-dk ab initio data. Spectator modes are treated adiabatically via inclusion of curvilinear projected frequencies. The total scattering wave function is expanded in a vibronic basis set and close-coupled equations are solved via R-matrix propagation. Ground state thermal rate constants for forward and reverse reactions agree well with experiment. Multi-surface reaction probabilities, integral cross sections, and initial-state selected branching ratios all highlight the importance of vibrational energy in mediating nonadiabatic transition. Electronically excited state dynamics are seen to play a small but significant role as consistent with experimental conclusions. (C) 2011 American Institute of Physics. [doi:10.1063/1.3592732

HABITAT USE BY GREATER SANDHILL CRANES IN WYOMING

Wyoming suppors approximately 20% of the Rocky Mountain population (RMP) of greater sandhill cranes (Grus canadensis tabida), as well as a number of whooping cranes (Grus americana) from the Grays Lake, Idaho flock. Cranes begin arriving on post-migration staging areas in Wyoming in mid-March and disperse to summer habitat in April or May, depending on snow cover. Fall pre-migration, staging peaks around mid-September; most cranes leave the state by 1 October. Wet meadows and gram fIelds were the major habitat types used by cranes in Wyoming 1985-1987. Use in these types ranged from 69- 100% of total observations in any given 2-week period. Important grains included barley, wheat and oats. Wet meadows were typically either seasonally flooded wetlands or flood-irrigated haylands. Alfalfa fields and cattailbulrush (Typha sp./Scirpus sp.) marshes were also important habitats for cranes