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L. Pillier C. Moreau X. Mercier J.F. Pauwels P. Desgroux 《Applied physics. B, Lasers and optics》2002,74(4-5):427-434
Cavity ring-down spectroscopy (CRDS) is used to measure the NO mole fraction formed in the burnt gases of low-pressure premixed
flames. It is shown that the line-of-sight absorption is greatly increased by the contribution of the NO molecules surrounding
the burner. This contribution has been quantified by developing a mathematical procedure taking into account the spatial and
spectral features of the CRDS measurement. Calculations have been undertaken in the general case of a stable species not consumed
in the flame. The most sensitive parameter is the temperature both in the flame and outside the flame. Simulations allow the
selection of the best spectroscopic transitions for a given flame (i.e. a given temperature profile), ensuring the weakest
influence of the inaccuracy affecting the temperature determination. High quantum states belonging to the A–X (0–1) band of
NO have been found to be the most valuable and have led to a NO mole fraction determination with an accuracy of ±13%. NO absorption
in the flame was completely masked using the A–X (0–0) band. Finally, the prompt-NO mole fraction formed in a methane/air
flame stabilized at 33 Torr is obtained by combining CRDS and laser induced fluorescence techniques.
Received: 12 October / Revised version: 1 February 2002 / Published online: 14 March 2002 相似文献
3.
The CRONE suspension, French acronym of “suspension à Comportement Robuste d’Ordre Non Entier”, results from a traditional suspension system whose spring and damper are replaced by a mechanical and hydropneumatic system defined by a fractional (so-called non-integer) order force–displacement transfer function. ‘ling, frequency-domain robust control design methodology, optimal approach, stability analysis and performance are presented in this paper. 相似文献
4.
Florence Robaut Alexandre Crisci Madeleine Durand-Charre Danielle Jouanne 《Microscopy and microanalysis》2006,12(4):331-334
The carbon contents in carburized steels were investigated by electron probe microanalysis (EPMA) for a range of carbon levels in the solid solution less than 1 wt%. This article describes the difficulties encountered with the classic analytical procedure using the k ratio of X-ray intensities and the phi(rhoz) model. Here, a suitable calibration curve method is presented with emphasis on the metallographic study of standard specimens and on the carbon decontamination of samples. 相似文献
5.
After a review of 1-perfluoroalkene RFCFCF2 synthesis, with RFC4F9, C5F11, C6F13, we have studied their fine structures by 19F N.M.R. This study has led us to first generalize the rules set for the chemical shifts and coupling constants of olefinic fluorine atoms of fluoropropene and their derivatives. Then, we have been able to determinate unambiguously the chemical shifts of the difluoromethylene groups of the perfluorinated chains. We have thus shown, by irradiation, that inversions may take place in the chemical shifts of the CF2 groups at the β and γ position of the double bond. 相似文献
6.
Benzylic fluorides, as well as five-membered heterocycles, have been obtained in high ee’s through cycloaddition reactions starting from easily accessible optically active propargylic fluorides. 相似文献
7.
A number of α-β acetylenic carbinols RFCCC(OH)RR′, in which the acetylenic proton was substituted by a F-alkyl group, were first prepared, from a classical reaction of (F-alkynyl)- lithium derivatives RFCCLi upon various carbonyl compounds.On another hand, the reaction of propargyl bromide metallic complexes (organoaluminic, or ultrasonic irradiation activated organozinc) upon some polyfluorinated ketones RFCOR led to the formation, in convenient yields, of the propargylic carbinols HCCCH2C(OH)RRF.The synthesis and properties of these series of new (F-alkyl) substituted acetylenic and propargylic alcohols are described and discussed. 相似文献
8.
Vugts DJ Jansen H Schmitz RF de Kanter FJ Orru RV 《Chemical communications (Cambridge, England)》2003,(20):2594-2595
In a multi-component reaction (MCR) of a phosphonate, nitriles, aldehydes and isocyanates, N3-functionalised dihydropyrimidines can be synthesised efficiently via a Horner-Emmons/aza Diels-Alder pathway. 相似文献
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We examine the steady-state flux of particles diffusing in a one-dimensional finite chain with Sinai-type disorder, i.e., the system in which in addition to the thermal noise, particles are subject to a stationary random-correlated in space Gaussian force. For this model we calculate the disorder average (over configurations of the random force) flux exactly for arbitrary values of system's parameters, such as chain lengthN, strength of the force, and temperature. We prove that within the limitN1 the average flux decreases withN as J(N)=C/N and thus confirm our recent predictions that the flux in the discrete-space Sinai model is anomalous. 相似文献