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201.
202.
In an early study [H. Tran, D. Jacquemart, J.Y. Mandin, N. Lacome, JQSRT 109 (2008) 119-131], line mixing effects of the ν6 band of methyl bromide were observed and modeled at room temperature. In the present work, line mixing effects have been considered at low temperatures using state-to-state collisional rates which were modeled by a fitting law based on the energy gap and a few fitting parameters. To validate the model, several spectra of methyl bromide perturbed by nitrogen have been recorded at various temperatures (205-299 K) and pressures (230-825 hPa). Comparisons between measured spectra and calculations using both direct calculation from relaxation operator and Rosenkranz profile have been performed showing improvement compared to the usual Lorentz profile. Note that the temperature dependence of the spectroscopic parameters has been taken into account using results of previous studies. 相似文献
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205.
L. Gomez H. Tran A. Perrin R.R. Gamache A. Laraia J. Orphal P. Chelin C.E. Fellows J.-M. Hartmann 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(9-10):675-686
In an earlier study [Flaud JM, Brizzi G, Carlotti M, Perrin A, Ridolfi M. MIPAS database: validation of HNO3 line parameters using MIPAS satellite measurements. Atmos Chem Phys 2006;6:1–12] the HNO3 line parameters in the HITRAN spectroscopic database have recently been revisited in the interval corresponding to the MIPAS spectral range. For the 11.3 μm region these updates involve the line positions for the {ν5, 2ν9} bands, and the intensities. However, comparisons between observed spectra recorded by MIPAS and the calculated ones in the 600–950 cm?1 region still show significant disagreements. The goal of the present paper is to solve some of these problems. Based on the analysis of N2-broadened HNO3 laboratory spectra recorded with a Fourier transform instrument, a new HNO3 database was generated, including the following improvements: (i) approximate parameters for the ν5+ν7?ν7 and ν5+ν6?ν6 hot bands have been added, and (ii) the intensities for the ν6 and ν8 bands have been updated. (iii) The air broadening and its temperature dependence, calculated using a semi-classical approach, have been added for each HNO3 transition. (iv) Finally, line-mixing effects have been pointed out, particularly in the ν5+ν9?ν9 Q branch, and an approach correctly modeling the resulting spectral shape is proposed. 相似文献
206.
Weiwei Deng James F. Klemic Xiaohui Li Mark A. Reed Alessandro Gomez 《Proceedings of the Combustion Institute》2007,31(2):2239-2246
The use of hydrocarbons is very appealing for the realization of high energy density power sources, so long as the fuel can be stored in the liquid phase. As a result, except for the most volatile hydrocarbons, a miniaturized combustor must rely on a good design of the fuel atomizer, which should yield small, rapidly evaporating droplets to generate the fuel vapor promptly, mix it with the oxidizer and subsequently burn it with the attending heat release. To achieve this goal, we relied on the use of multiplexed electrosprays and a catalytic reactor for fuel conversion consisting of a pack of catalyst impregnated meshes (Microliths®). Fuel dispersion was achieved by microfabricating the fuel distributor in Si using deep reactive ion etching. Tests were performed using JP-8 as the liquid fuel. Preliminary experiments in a 0.8 cm3 optically accessible combustor, enabling the measurements of droplet size and velocity, revealed that the spreading of the electrospray by Coulombic repulsion is the phenomenon controlling the volume of the mixing/evaporation chamber. Droplet evaporation occurs in the thin (Peclet number dependent) thermal layer preceding the catalytic section of the combustor. Subsequent system optimization in a fully ceramic combustor yielded a volumetric heat release rate as large as 270 MW/m3, a value that is of the same order as that of conventional gas turbines. The small overall combustor volume, at only 0.22 cm3, suggests that the large volumetric energy density was achieved despite the device large surface-to-volume ratio and attending heat losses. The fuel was fully oxidized, with CO/CO2 ratios well under 1% over a range of equivalence ratios. Inspection of the combustor inner walls after operating continuously for 10 h, revealed no traces of deposits. The design has the potential of being scaled either up or down, depending on power needs. 相似文献
207.
Plateaus in water adsorption isotherms on hydroxylated BeO surfaces suggest significant differences between the hydroxylated (1 0 0) and (0 0 1) surface structures and reactivities. Density functional theory structures and energies clarify these differences. Using relaxed surface energies, a Wulff construction yields a prism crystal shape exposing long (1 0 0) sides and much smaller (0 0 1) faces. This is consistent with the BeO prisms observed when beryllium metal is oxidized. A water oxygen atom binds to a single surface beryllium ion in the preferred adsorption geometry on either surface. The water oxygen/beryllium bonding is stronger on the surface with greater beryllium atom exposure, namely the less-stable (0 0 1) surface. Water/beryllium coordination facilitates water dissociation. On the (0 0 1) surface, the dissociation products are a hydroxide bridging two beryllium ions and a metal-coordinated hydride with some surface charge depletion. On the (1 0 0) surface, water dissociates into a hydroxide ligating a Be atom and a proton coordinated to a surface oxygen but the lowest energy water state on the (1 0 0) surface is the undissociated metal-coordinated water. The (1 0 0) fully hydroxylated surface structure has a hydrogen bonding network which facilitates rapid proton shuffling within the network. The corresponding (0 0 1) hydroxylated surface is fairly open and lacks internal hydrogen bonding. This supports previous experimental interpretations of the step in water adsorption isotherms. Further, when the (1 0 0) surface is heated to 1000 K, hydroxides and protons associate and water desorbs. The more open (0 0 1) hydroxylated surface is stable at 1000 K. This is consistent with the experimental disappearance of the isotherm step when heating to 973 K. 相似文献
208.
Theoretically simulated UV-visible photoabsorption spectra of the buckyonions are compared with the most recent and complete experimental data. The very good agreement found provides support for our theoretical model of the buckyonions and allows for a detailed analysis of the correspondence between these spectra and the UV interstellar extinction feature. The excellent agreement found between the theoretical and observational features and the consistency of the former with the observational data constraints gives very strong support for the buckyonion origin of the UV interstellar spectrum. 相似文献
209.
基于文献[5]中我们所获得的本征型光学双稳系统的熵产生表达式,本文证明该系统(光学被动腔)能够很好地满足最小熵产生定理。
关键词: 相似文献
210.
D.E. Gustafson J.Gomez Del Campo R.L. Robinson P.H. Stelson P.D. Miller J.K. Bair 《Nuclear Physics A》1976,262(1):96-112
The structure of 26Mg has been investigated by means of the 12C(18O, α) reaction. Several previously unknown states were populated between excitation energies of 0 to 16 MeV. Excitation functions were measured for 126 states for bombarding energies between 43.2 and 45.9 MeV in 300 keV steps at a lab angle of 7°. The experimental energy averaged differential cross sections were compared with statistical model calculations and good agreement was obtained for the states whose spins and parities were previously established. The statistical model calculations were used to suggest the spins and parities for the rest of the states. In particular, candidates for 6+ and 8+ states were interpreted as members of three rotational bands in 26Mg: the ground-state band, the K = 2+ band based on the 2.938 MeV 2+ state, and a K = 0+ band based on the 3.588 MeV 0+ state. Back bending of the yrast band is observed and it is suggested that it may be due to band crossing of the ground-state and first excited K = 0+ bands. 相似文献