35 research outputs found
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Reduction of Large Detailed Chemical Kinetic Mechanisms for Autoignition Using Joint Analyses of Reaction Rates and Sensitivities
A new technique of reduction of detailed mechanisms for autoignition, which is based on two analysis methods is described. An analysis of reaction rates is coupled to an analysis of reaction sensitivity for the detection of redundant reactions. Thresholds associated with the two analyses have a great influence on the size and efficiency of the reduced mechanism. Rules of selection of the thresholds are defined. The reduction technique has been successfully applied to detailed autoignition mechanisms of two reference hydrocarbons: n-heptane and iso-octane. The efficiency of the technique and the ability of the reduced mechanisms to reproduce well the results generated by the full mechanism are discussed. A speedup of calculations by a factor of 5.9 for n-heptane mechanism and by a factor of 16.7 for iso-octane mechanism is obtained without losing accuracy of the prediction of autoignition delay times and concentrations of intermediate species
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Detailed Chemical Kinetic Modeling of Cyclohexane Oxidation
A detailed chemical kinetic mechanism has been developed and used to study the oxidation of cyclohexane at both low and high temperatures. Reaction rate constant rules are developed for the low temperature combustion of cyclohexane. These rules can be used for in chemical kinetic mechanisms for other cycloalkanes. Since cyclohexane produces only one type of cyclohexyl radical, much of the low temperature chemistry of cyclohexane is described in terms of one potential energy diagram showing the reaction of cyclohexyl radical + O{sub 2} through five, six and seven membered ring transition states. The direct elimination of cyclohexene and HO{sub 2} from RO{sub 2} is included in the treatment using a modified rate constant of Cavallotti et al. Published and unpublished data from the Lille rapid compression machine, as well as jet-stirred reactor data are used to validate the mechanism. The effect of heat loss is included in the simulations, an improvement on previous studies on cyclohexane. Calculations indicated that the production of 1,2-epoxycyclohexane observed in the experiments can not be simulated based on the current understanding of low temperature chemistry. Possible 'alternative' H-atom isomerizations leading to different products from the parent O{sub 2}QOOH radical were included in the low temperature chemical kinetic mechanism and were found to play a significant role
Vectorial Ribaucour Transformations for the Lame Equations
The vectorial extension of the Ribaucour transformation for the Lame
equations of orthogonal conjugates nets in multidimensions is given. We show
that the composition of two vectorial Ribaucour transformations with
appropriate transformation data is again a vectorial Ribaucour transformation,
from which it follows the permutability of the vectorial Ribaucour
transformations. Finally, as an example we apply the vectorial Ribaucour
transformation to the Cartesian background.Comment: 12 pages. LaTeX2e with AMSLaTeX package
Classification of integrable Weingarten surfaces possessing an sl(2)-valued zero curvature representation
In this paper we classify Weingarten surfaces integrable in the sense of
soliton theory. The criterion is that the associated Gauss equation possesses
an sl(2)-valued zero curvature representation with a nonremovable parameter.
Under certain restrictions on the jet order, the answer is given by a third
order ordinary differential equation to govern the functional dependence of the
principal curvatures. Employing the scaling and translation (offsetting)
symmetry, we give a general solution of the governing equation in terms of
elliptic integrals. We show that the instances when the elliptic integrals
degenerate to elementary functions were known to nineteenth century geometers.
Finally, we characterize the associated normal congruences
Autoinflammation à haute pression. Conception, réalisation et test d’une machine à compression rapide
Une machine à compression rapide originale a été construite pour l’étude de l’autoinflammation des hydrocarbures et la validation des mécanismes réactionnels à haute pression dans la gamme de température 600-900 K environ. Cette machine est pilotée par microordinateur et est munie d’un système d’échantillonnage. Les problèmes liés à la détermination des températures et la vitesse de compression des gaz sont discutés. Divers exemples d’autoinflammation sont donnés notamment dans le cas d’autoinflammations "douces" et "sévères"
National perspectives on non-animal approaches for quality control and batch release testing of biologicals and the influence of WHO guidelines
A detailed experimental study of n-propylcyclohexane autoignition in lean conditions
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