Use of an air-assisted fuel nozzle to reduce idle emissions of a jt8d engine combustor

Tests were performed at typical engine idle conditions on a single-can JT8D combustor installed in a 24 centimeter (9.45 in.) housing to evaluate the effect of an air-assist nozzle on reducing exhaust emissions. By injecting high-pressure air through the secondary-flow passage of a standard duplex fuel nozzle, it was possible to reduce hydrocarbon emissions from 840 parts per million to 95 parts per million and carbon monoxide emissions from 873 parts per million to 258 parts per million. NOX emissions increased slightly from 18 parts per million to 22 parts per million. An air-assist differential pressure of only 20.1 newtons per square centimeter (29.1 psi) and an airflow rate of only 0.22 percent of the total combustor airflow was required

Boundary lubrication, thermal and oxidative stability of a fluorinated polyether and a perfluoropolyether triazine

Boundary lubricating characteristics, thermal stability, and oxidation-corrosion stability were determined for a fluorinated polyether and a perfluoropolyether triazine. A ball-on-disk apparatus, a tensimeter, and oxidation-corrosion apparatus were used. Results were compared to data for a polyphenyl ether and a C-ether. The polyether and triazine yielded better boundary lubricating characteristics than either the polyphenyl ether or C-ether. The polyphenyl ether had the greatest thermal stability (443 C) while the other fluids had stabilities in the range 389 to 397 C. Oxidation-corrosion results indicated the following order of stabilities: perfluoropolyether trizine greater than polyphenyl ether greater than C-ether greater than fluorinated polyether

c(2x2) Interface Alloys in Co/Cu Multilayers - Influence on Interlayer Exchange Coupling and GMR

The influence of a c(2x2) ordered interface alloy of 3d transition metals at the ferromagnet/nonmagnet interface on interlayer exchange coupling (IXC), the formation of quantum well states (QWS) and the phenomenon of Giant MagnetoResistance is investigated. We obtained a strong dependence of IXC on interface alloy formation. The GMR ratio is also strongly influenced. We found that Fe, Ni and Cu alloys at the interface enhance the GMR ratio for in-plane geometry by nearly a factor of 2.Comment: 14 pages, 5 figures, 1 table, subm. to PR

Opening angles, Lorentz factors and confinement of X-ray binary jets

We present a collation of the available data on the opening angles of jets in X-ray binaries, which in most cases are small (less than 10 degrees). Under the assumption of no confinement, we calculate the Lorentz factors required to produce such small opening angles via the transverse relativistic Doppler effect. The derived Lorentz factors, which are in most cases lower limits, are found to be large, with a mean greater than 10, comparable to those estimated for AGN and much higher than the commonly-assumed values for X-ray binaries of 2 to 5. Jet power constraints do not in most cases rule out such high Lorentz factors. The upper limits on the opening angles show no evidence for smaller Lorentz factors in the steady jets of Cygnus X-1 and GRS 1915+105. In those sources in which deceleration has been observed (notably XTE J1550-564 and Cygnus X-3), some confinement of the jets must be occurring, and we briefly discuss possible confinement mechanisms. It is however possible that all the jets could be confined, in which case the requirement for high bulk Lorentz factors can be relaxed.Comment: 11 pages, 4 figures (2 colour), accepted for publication in MNRA

High speed simulation of flexible multibody dynamics

A multiflexible body dynamics code intended for fast turnaround control design trades is described. Nonlinear rigid body dynamics and linearized flexible dynamics combine to provide efficient solution of the equations of motion. Comparison with results from the DISCOS code provide verification of accuracy

On the Nature of X-ray Surface Brightness Fluctuations in M87

X-ray images of galaxy clusters and gas-rich elliptical galaxies show a wealth of small-scale features which reflect fluctuations in density and/or temperature of the intra-cluster medium. In this paper we study these fluctuations in M87/Virgo, to establish whether sound waves/shocks, bubbles or uplifted cold gas dominate the structure. We exploit the strong dependence of the emissivity on density and temperature in different energy bands to distinguish between these processes. Using simulations we demonstrate that our analysis recovers the leading type of fluctuation even in the presence of projection effects and temperature gradients. We confirm the isobaric nature of cool filaments of gas entrained by buoyantly rising bubbles, extending to 7' to the east and south-west, and the adiabatic nature of the weak shocks at 40" and 3' from the center. For features of 5--10 kpc, we show that the central 4'x 4' region is dominated by cool structures in pressure equilibrium with the ambient hotter gas while up to 30 percent of the variance in this region can be ascribed to adiabatic fluctuations. The remaining part of the central 14'x14' region, excluding the arms and shocks described above, is dominated by apparently isothermal fluctuations (bubbles) with a possible admixture (at the level of about 30 percent) of adiabatic (sound waves) and by isobaric structures. Larger features, of about 30 kpc, show a stronger contribution from isobaric fluctuations. The results broadly agree with an AGN feedback model mediated by bubbles of relativistic plasma.Comment: 16 pages, submitted to Ap

Single stage experimental evaluation of variable geometry guide vanes and stator blading. Part 5 - Overall performance for variable camber guide vane and stator B with radial and circumferential inlet flow distortion

Inlet flow distortion effects on single stage variable geometry guide vanes and stator

Integrity static analysis of COTS/SOUP

This paper describes the integrity static analysis approach developed to support the justification of commercial off-the-shelf software (COTS) used in a safety-related system. The static analysis was part of an overall software qualification programme, which also included the work reported in our paper presented at Safecomp 2002. Integrity static analysis focuses on unsafe language constructs and “covert” flows, where one thread can affect the data or control flow of another thread. The analysis addressed two main aspects: the internal integrity of the code (especially for the more critical functions), and the intra-component integrity, checking for covert channels. The analysis process was supported by an aggregation of tools, combined and engineered to support the checks done and to scale as necessary. Integrity static analysis is feasible for industrial scale software, did not require unreasonable resources and we provide data that illustrates its contribution to the software qualification programme