Spontaneous ignition characteristics of gaseous hydrocarbon-air mixtures

Experiments are conducted to determine the spontaneous ignition delay times of gaseous propane, kerosine vapor, and n-heptane vapor in mixtures with air, and oxygen-enriched air, at atmospheric pressure. Over a range of equivalence ratios from 0.2 to 0.8 it is found that ignition delay times are sensibly independent of fuel concentration. However, the results indicate a strong dependence of delay times on oxygen concentration. The experimental data for kerosine and propane demonstrate very close agreement with the results obtained previously by Mullins and Lezberg respectively

Spontaneous Ignition Characteristics of Hydrocarbon Fuel-air Mixtures

Although the subject of spontaneous ignition of liquid fuels has received considerable attention in the past, the role of fuel evaporation in the overall spontaneous ignition process is still unclear. A main purpose of this research is to carry out measurements of ignition delay times, using fuels of current and anticipated future aeronautical interest, at test conditions that are representative of those encountered in modern gas turbine engines. Attention is focused on the fuel injection process, in particlar the measurement and control of man fuel drop size and fuel-air spatial distribution. The experiments are designed to provide accurate information on the role of fuel evaporation processes in determining the overall ignition delay time. The second objective is to examine in detail the theoretical aspects of spontaneous ignition in order to improve upon current knowledge and understanding of the basic processes involved, so that the results of the investigation can find general and widespead application

On the optimality of interest-bearing reserves in economies of overlapping generations

Econometrics

Optical and electrical activity of defects in rare earth implanted Si

A common technique for introducing rare earth atoms into Si and related materials for photonic applications is ion implantation. It is compatible with standard Si processing, and also allows high, non-equilibrium concentrations of rare earths to be introduced. However, the high energies often employed mean that there are collision cascades and potentially severe end-of-range damage. This paper reports on studies of this damage, and the competition it may present to the optical activity of the rare earths. Er-, Si, and Yb-implanted Si samples have been investigated, before and after anneals designed to restore the sample crystallinity. The electrical activity of defects in as-implanted Er, Si, and Yb doped Si has been studied by Deep Level Transient Spectroscopy (DTLS) and the related, high resolution technique, Laplace DLTS (LDLTS), as a function of annealing. Er-implanted Si, regrown by solid phase epitaxy at 600degrees C and then subject to a rapid thermal anneal, has also been studied by time-resolved photoluminescence (PL). The LDLTS studies reveal that there are clear differences in the defect population as a function of depth from the surface, and this is attributed to different defects in the vacancy-rich and interstitial-rich regions. Defects in the interstitial-rich region have electrical characteristics typical of small extended defects, and these may provide the precursors for larger structural defects in annealed layers. The time-resolved PL of the annealed layers, in combination with electron microscopy, shows that the Er emission at 1.54microns contains a fast component attributed to non-radiative recombination at deep states due to small dislocations. It is concluded that there can be measurable competition to the radiative efficiency in rare-earth implanted Si that is due to the implantation and is not specific to Er.</p

Should bank reserves earn interest?

This article examines the effects and desirability of paying interest on required reserves. Scott Freeman and Joseph Haslag demonstrate that a policy of paying interest on reserves can make everyone better off, even if the interest must be financed by a tax on capital. An essential part of this policy is an open market operation that offsets any changes in the value of money.Bank reserves

Device measures fluid drag on test vehicles

Electromechanical drag balance device measures the aerodynamic drag force acting on a vehicle as it moves through the atmosphere and telemeters the data to a remote receiving station. This device is also used for testing the hydrodynamic drag characteristics of underwater vehicles

Thin Films of 3He -- Implications on the Identification of 3 He -A

Recently the identification of 3He-A with the axial state has been questioned. It is suggested that the A-phase can actually be in the axiplanar state. We point out in the present paper that experiments in a film geometry may be useful to distinguish the above two possibilities. In particular a second order phase transition between an axial and an axiplanar state would occur as a function of thickness or temperature.Comment: 3 pages, no figures latex- revtex aps accepted by J. of Low Temperature Physic

Air frame drag balance Patent

Device for measuring drag forces in flight test

A mass reduction effort of the electric and hybrid vehicle

Weight reduction, cost competitiveness, and elimination of the intrusion beam resulted from the redesign and fabrication using composite materials of the door outer panel and intrusion beam from a Chevrolet Impala. The basis of the redesign involved replacing these two steel parts with a single compression molding using the unique approach of simultaneously curing a sheet molding compound outside panel with a continuous glass fiber intrusion strap. A weight reduction of nearly 11 pounds per door was achieved. Additional weight savings are possible by taking advantage of the elimination of the intrusion beam to design thinner door structures. The parts consolidation approach allows the composite structure to be cost competitive with the original steel design for both the lower production car models and for the near to midterm production vehicles using current state of the art composite production techniques. The design, prototype fabrication, costing, material, properties and compression molding production requirements are discussed