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981.
Athina P. Bougioukou Apostolos P. Leros Vassilios Papakonstantinou 《Applied Mathematical Modelling》2008
This paper presents a new method for modeling amplitude and frequency non-stationary earthquake ground motions using a scalar first order dynamic mean reverting stochastic differential equation driven by Brownian motion with parametric time varying coefficients. It determines the proper relationship between these time varying parametric coefficients and presents the statistical and probability distribution characteristics of the response solution. It demonstrates the applicability of the method by presenting some simulations of amplitude and frequency non-stationary earthquake ground motions. The verification of the amplitude and frequency non-stationary contents of the mean reverting stochastic ground motions is demonstrated using the Hilbert–Huang transform method. Also a corresponding interpretation between the coefficients of the proposed model and the coefficients of the usual oscillatory second order differential equation driven by white Gaussian noise is presented along with some comments how it can be applied to simulate ground motions consistent with acceleration target records such as boxcar, trapezoidal, other exponential functions, or compound and target records at source, near field, and far field distances. 相似文献
982.
Experimental measurements of power spectra of a single longitudinal and transverse mode ring dye laser are presented that reveal the critical slowing down of the laser near threshold. External pump noise serves as a probe of the frequency response of the dye laser. Detailed comparisons of the spectral characteristics with computer simulations and an approximate analytic theory are given. The dynamics of spatial pattern formation in a multimode dye laser is examined through measurements of first-passage-time distributions. A comparison of the experiments with computer simulations based on a simple theoretical model of the two-mode laser shows qualitative agreement. These measurements indicate that there are a variety of complex phenomena associated with the transverse mode pattern formation dynamics that need to be addressed theoretically and studied further experimentally. 相似文献
983.
The geometry, frequency, and intensity of the vibrational bands of imidazo[1,2-a]pyridine (which is abbreviated as impy) were
obtained by the density functional theory (DFT) calculations with BLYP, B3LYP, and B3PW91 functionals and 6-31G(d) basis set.
The optimized geometric bond lengths and bond angles are in good agreement with the available X-ray data. The infrared spectrum
of imidazo[1,2-a]pyridine was computed by the DFT method in order to reproduce the vibrational wavenumbers and intensities
with an accuracy, which allows reliable vibrational assignments. Total energy distribution and isotopic shifts have been calculated
in order to help for the perfect assignment of the vibrational modes. The zinc halide complexes Zn(impy)2X2 [X = Cl, Br, and I] have also been synthesized. The compounds were characterized using the elemental analysis, FT-IR spectra,
and quantum chemical calculations. The geometry optimization of Zn(impy)2X2 yields distorted tetrahedral environment around Zn ion. 相似文献
984.
The reaction between tannic acid and metallic iron was studied using infrared and Mössbauer spectroscopy. Iron converts to sparingly soluble and amorphous ferric tannate complexes. The degree of conversion was followed from 1 day to 6 months. In the very early stages of reaction the product consists of a mono-type complex, while in the later stages a mixture of mono- and bis-type complexes were formed. The conversion reaction of metallic iron to tannate complexes follows a first-order reaction kinetics. 相似文献
985.
许长谭 《光谱学与光谱分析》2001,(4)
应用三角晶场中d2 (d8)电子组态包括静电相互作用和自旋 轨道耦合作用的强场能量矩阵 ,采用完全对角化方法 ,精确地计算了具有D3d 对称的Ni2 + :CsMgCl3 的光学吸收谱和EPR谱。理论结果与实验值符合得很好。 相似文献
986.
Jamila Ghamri Herv Baussart Michel le Bras Jean-Marie Leroy 《Journal of Physics and Chemistry of Solids》1989,50(12):1237-1244
The mixed oxides BixEu1−xVO4 and BiyGd1−yVO4 crystallize in a zircon-type structure, for 0 <x < 0.6 and 0 < y < 0.64, and in a fergusonite-type structure, for 0.94 < x < 1 and 0.93 < y < 1. A process of competition between the dominant and the constrained effects of the lone-pair 6s2 of Bi3+ is discussed. The diffuse reflectance spectroscopic studies of these mixed oxides are presented. The observed broad bands are attributed to charge transfer processes and the sharp peaks in the BixEu1−xVO4 spectra are ascribed to intra-configurational 4f – 4ftransitions of the Eu3+ ion. The broad absorption shift in BiLnVO4 (Ln : Eu and Gd) compounds to the longer wavelengths range, when Bi is introduced in the LnVO4 lattice, is ascribed to charge transfer processes in a Bi-VO4 center and are interpreted assuming a Jahn-Teller effect in the excited state of Bi3+. The concept of an internal pressure of Bi3+ ions is also used to explain the broad A-band shifts. 相似文献
987.
V. Vescoli F. Zwick W. Henderson L. Degiorgi M. Grioni G. Gruner L.K. Montgomery 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(3):503-511
Combined optical and photoemission experiments on the quasi-one dimensional Bechgaard salts reveal the non-Fermi liquid character
of these prototype quasi-one dimensional interacting electron systems. We show that various aspects of the exotic normal state
properties along the chains are consistent with the predictions of the Tomonaga-Luttinger liquid theory. We also discuss the
effect of interchain coupling on the insulator-metal transition, associated with the electron confinement-deconfinement crossover.
Received 17 May 1999 and Received in final form 13 July 1999 相似文献
988.
V. V. Uglov V. I. Shimanski D. P. Rusalsky M. P. Samtsov 《Journal of Applied Spectroscopy》2008,75(4):546-549
The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the
UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles
changes during the treatment.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 524–528, July–August, 2008. 相似文献
989.
偶氮类化合物热相变动态过程的二维相关拉曼光谱研究 总被引:1,自引:0,他引:1
利用变温傅里叶变换拉曼光谱(FT-Raman)研究含偶氮苯基长链脂肪酸化合物8A5H固体的热相变。二维相关光谱分析技术被应用到以温度为变量的同步和异步相关计算,目的在于研究该化合物中不同基团在热相变过程中取向变化过程以及变化趋势、步骤等一系列的动态结构变化。展示了研究偶氮类化合物热致相变过程中结构动态新的研究方法,同时也为二维相关光谱的应用拓宽了新的研究领域。 相似文献
990.
The excitation spectra in the wavelength range of 19—40 nm for highly ionized sulphur ions were measured by using the beam-foil
method at the Heavy lon Research Facility in Lanzhou. In this experiment, more than 30 spectral lines were observed, which
belonged to the transitions of the excitation energy levels for highly ionized SX—SXV ions, and 5 new lines were determined.
The experimental results were compared with those from other experiments and theoretical calculations. 相似文献