37,104 research outputs found
An Autoignition Study of iso-Butanol: Experiments and Modeling
The autoignition delays of iso-butanol, oxygen, and nitrogen mixtures have
been measured in a heated rapid compression machine (RCM). At compressed
pressures of 15 and 30 bar, over the temperature range 800-950 K, and for
equivalence ratio of = 0.5 in air, no evidence of an NTC region of
overall ignition delay is found. By comparing the data from this study taken at
= 0.5 to previous data collected at = 1.0 (Weber et al. 2013), it
was found that the = 0.5 mixture was less reactive (as measured by the
inverse of the ignition delay) than the = 1.0 mixture for the same
compressed pressure. Furthermore, a recent chemical kinetic model of
iso-butanol combustion was updated using the automated software Reaction
Mechanism Generator (RMG) to include low- temperature chain branching pathways.
Comparison of the ignition delays with the updated model showed reasonable
agreement for most of the experimental conditions. Nevertheless, further work
is needed to fully understand the low temperature pathways that control
iso-butanol autoignition in the RCM.Comment: 6 pages, 4 figures, 8th US National Combustion Meetin
The low energy expansion of the one-loop type II superstring amplitude
The one-loop four-graviton amplitude in either of the type II superstring
theories is expanded in powers of the external momenta up to and including
terms of order s^4 log s R^4, where R^4 denotes a specific contraction of four
linearized Weyl tensors and s is a Mandelstam invariant. Terms in this series
are obtained by integrating powers of the two-dimensional scalar field theory
propagator over the toroidal world-sheet as well as the moduli of the torus.
The values of these coefficients match expectations based on duality relations
between string theory and eleven-dimensional supergravity.Comment: harvmac (b), 25 pages, 3 eps figures. v2: Factors of 2 corrected.
Conclusion unchange
Quartz crystal microbalance use in biological studies
Design, development, and applications of quartz crystal microbalance are discussed. Two types of crystals are used. One serves as reference and other senses changes in mass. Specific application to study of bacterial spores is described
A solution to Einstein’s field equations for a tachyonic gas: possible astrophysical applications
In this paper we show that a change in the signs of some of the metric components of the solution of the field equations for the classical cosmic string results in a solution which we interpret as a time-dependent wall composed of tachyons. We show that the walls have the property of focusing the paths of particles which pass through them. As an illustration of this focusing, we demonstrate the results of a simple simulation of the interaction between one such tachyon wall and a rotating disk of point masses. This interaction leads to the temporary formation of spiral structures. These spiral structures exist for a time on the order of one galactic rotation
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