This investigation assesses the benefits of retrofitting a diesel micro-pilot ignition system on a Cooper-Bessemer GMV-4TF two-stroke cycle natural gas engine with a 14” (36 cm) bore and a 14” (36 cm) stroke. The pilot fuel injectors are mounted through an adaptor in one of the spark plug holes in a set of dual-spark plug heads. A high pressure, common-rail, diesel fuel delivery system is employed and customizable power electronics control the current signal to the pilot injectors. Pilot fuel is supplied by a variable displacement, high-pressure pump that is driven with an electric motor. Software is developed that interfaces with the pump and controls and monitors the fuel rail pressure. Micro-pilot quantities from 11.5 to 20 mm3 (.0007 to .0012 in3) are explored at rail pressures from 200 to 1400 bar (2,900 to 20,300 psig). Three independent variables, pilot ignition timing, pilot fuel quantity, and pilot fuel rail pressure, are manipulated. An optimization sequence is performed to minimize total fuel consumption.
Fourier transform techniques are used to obtain an approximate expression for the response of a quantum mechanical two-level system to a small monochromatic applied electric field. A comparison with the results of a numerical integration of the differential equations shows that the approximation is equally satisfactory close to and far from resonance. The method is easily extended to two or more applied fields.On utilise des techniques de transformkes de Fourier pour obtenir une expression approximative de la rkponse d'un systkme quantique B deux niveaux, lorsqu'on lui applique un champ Clectrique monochromatique de faible intensitk. La comparaison avec les rtsultats d'une inttgration numtrique des Cquations difftrentielles montre que l'approximation est Cgalement satisfaisante prks et loin de la rksonance. La mkthode peut facilement Etre gknCralisCe au cas de deux ou plusieurs champs appliquts.[Traduit par le journal]Can. J. Phys. 62. 741 (1984) 1. Introduction The equations describing a quantum mechanical twolevel system in a single monochromatic applied electric field are deceptively simple in appearance. Despite the extensive attention this problem has received over the last thirty years (see a review article by Dion and Hirschfelder (l)), there are no exact analytical solutions available in the literature. Approximate solutions have been obtained either by restricting the applied field frequency to values close to the resonance frequency of the system, the so-called rotating wave approximation (RWA), or by exploiting the fact that the solution must exhibit, in a special sense, the periodicity of the applied field. The precise form of this periodicity is dictated by Floquet's theorem (2). The extension of the problem to the case of a two-level system in two or more monochromatic fields is of some current physical interest (3-5). However, with two or more applied frequencies Floquet's theorem is no longer applicable and so the single frequency analysis, which works so well over a wide range of frequencies, is not available for exploitation in the multifield case. There is not the same restriction for the RWA. One can extend quite easily the RWA to the case of several fields (4, 5), but the results are valid only in a narrow frequency range.In this paper we describe an approximate method of solution for the two-level problem that works as well as the methods founded on Floquet's theorem and, moreover, can be extended to the multifield case. Our ap-
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