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71.
J.R. Dawson V.M. Rodriguez-Martinez A.J. Beale T. ODoherty 《Proceedings of the Combustion Institute》2005,30(2):1815-1822
An experimental study focusing on the temporal evolution of the global OH heat release (q′) and dynamic pressure (p′) from ignition to limit cycle conditions in an aerovalved pulse combustor has been carried out. The motivation of the work was to investigate how the thermo-acoustic relationships evolve, as very little is understood regarding how pressure and heat release couplings develop prior to establishing limit cycle conditions. The start-up experiments demonstrated that the total start-up sequences occurred within 100 ms and can be subdivided into three regimes: (i) ignition and decay; (ii) instability growth; and (iii) onset of limit cycle operation. The main results showed that upon ignition the high amplitude impulse pressure wave corresponded to the natural frequency of the pulse combustor at ambient gas temperature and was verified by an acoustic model. The pressure field over the growth period exhibited two main trends, either steady amplitude growth or a short delay interval followed by steady amplitude growth to limit cycle conditions. Overall, no reproducibility in frequency or phase during the growth period was observed pointing to the influence of strong non-linear interactions. When operating under limit cycle conditions, the heat release and pressure oscillations were in phase, possessed high levels of coherence, and exhibited narrow band frequency response at the operating frequency and several harmonics. 相似文献
72.
Urquhart AJ Williams FJ Vaughan OP Cropley RL Lambert RM 《Chemical communications (Cambridge, England)》2005,(15):1977-1979
Molecular orientation, which depends on surface coverage, determines whether or not catalytic hydrogenation is chemoselective. 相似文献
73.
Beshara CS Hall A Jenkins RL Jones TC Parry RT Thomas SP Tomkinson NC 《Chemical communications (Cambridge, England)》2005,(11):1478-1480
A mild, efficient and general method for the chemospecific alpha-oxygenation of aldehydes is described. Treatment of a series of aldehydes with N-tert-butyl-O-benzoyl hydroxylamine hydrochloride gives the corresponding alpha-oxygenated carbonyl via a proposed pericyclic rearrangement process. 相似文献
74.
Beale AM van der Eerden AM Kervinen K Newton MA Weckhuysen BM 《Chemical communications (Cambridge, England)》2005,(24):3015-3017
The potential of combined operando UV-Vis/Raman/XAFS has been explored by studying the active site and deactivation mechanism of silica- and alumina-supported molybdenum oxide catalysts under propane dehydrogenation conditions. 相似文献
75.
76.
E. M. L. Beale P. A. B. Hughes S. R. Broadbent 《The Journal of the Operational Research Society》1966,17(4):381-411
This paper outlines the approach made by The London Press Exchange to the media scheduling problem. A rather detailed simulation model of the way television and press schedules reach a target population has been set up. This is used to assess various alternative schedules, i.e. to give an effectiveness rating for each schedule. The marginal rate of return for various alterations to these schedules is also produced. Details of the mathematics in the model and of parts of the computer programs are given. Examples illustrate particular points and the general application. 相似文献
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78.
H. G. M. Edwards E. Beale N. C. Garrington J.M. Alia 《Journal of Raman spectroscopy : JRS》2007,38(3):316-322
FT‐Raman spectroscopic analysis of eight pigmented specimens from an important Hindu statue group, Kali Walking on Siva, acquired in 1895 but of indeterminate age and now in the Horniman Museum, London, has revealed some interesting and unusual combinations of coloured pigments including cinnabar, minium, lapis lazuli and red ochre. Several specimens showed evidence of organic additives, which have been attributed to shellac resins commonly believed to have been used on this type of statuary. The Raman spectroscopic results confirm that the predominant black pigment on the Kali figure is lamp black or soot, in contrast to the SEM‐EDX data that suggests the origin of this pigment as from bone black or ivory black from the presence of phosphorus. An eclectic range of white pigments have been identified in this group including lead white, barytes, calcite and anhydrite; rutile and anatase found on one specimen on the jackal in this group have been ascribed to recent unrecorded restoration. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
79.