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The properties of the negative parity states of55Fe and57Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states. 相似文献
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The effect of the radiative cooling of electrons on the gravitational collapse of cold dust grains with fluctuating electric
charge is investigated. We find that the radiative cooling as well as the charge fluctuations, both, enhance the growth rate
of the Jeans instability. However, the Jeans length, which is zero for cold grains and nonradiative plasma, becomes finite
in the presence of radiative cooling of electrons and is further enhanced due to charge fluctuations of grains resulting in
an increased threshold of the spatial scale for the Jeans instability. 相似文献
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The LSD (Logic for Structure Determination) program gener-ates organic molecular structures from 1D and 2D NMR data without resorting to chemical shift databases. Its use in the res-olution of natural product structure determination problems has been already reported in the literature. This paper describes how data and structures are internally represented and pro-cessed by LSD to build solution structures. 相似文献
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APPLICATION OF GENETIC ALGORITHM IN PARTICLE SIZE ANALYSIS BY MULTISPECTRAL EXTINCTION MEASUREMENTS 总被引:1,自引:0,他引:1
Gerard Grhan 《中国颗粒学报》2004,2(6):235-240
Both dependent and independent model algorithms are designed with genetic algorithm (GA) to retrieve aerosol size data from multispectral extinction measurements. Compared with the traditional dependent model algorithm, e.g., simplex, GA can locate the global optimized solution instead of local ones. As an independent model algonthm, when combined with B-splines, GA gives consistent results with Chahine and Phillip-Twomey-NNLS algorithms. Numerical simulations also show that GA has high stability and good resistance to relatively higher error levels. For a population size of 50 in the present paper, the feasible ranges for genetic operators Pc and pm are found to be [0.01, 0.5] and [0.01, 0.15], respectively, and the generation number Gen_Max should be larger than 250. 相似文献
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Infrared-to-visible wave-length conversion in the Yb3+−Er3+ doped phosphors system has been described by a simple three level model based on two ions mechanism. The excitation in the
range of 900–1000 nm of an IR-photon is first absorbed by Yb3+ ion as a sensitizer attributed to the resonant energy transition in Er3+ ion from 4
I
3/2 → 4
S
15/2 and 1
F
9/2 → 4
I
15/2, respectively for green and red emission. The essential energy transfer processes in this system i.e. upconversion from 4
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11/2 and 1
I
13/2, cross-relaxation from 4
S
3/2 and 1
F
9/2 are taken into account. The limitations of the rate-equation approach are examined with a focus on the underlying dynamics
of this rare-earth system. 相似文献
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LI YingQiu HU YangLi & LIU QuanSheng College of Mathematics Computing Sciences Changsha University of Science Technology Changsha China College of Mathematics Computer Sciences Hunan Normal University Changsha LMAM University of Bretgne-Sud BP Vannes France 《中国科学 数学(英文版)》2011,(7)
Let W be the limit of the normalized population size of a supercritical branching process in a varying or random environment. By an elementary method, we find sufficient conditions under which W has finite weighted moments of the form EWpl(W), where p > 1, l 0 is a concave or slowly varying function. 相似文献