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11.
The thiourea adducted saturated hydrocarbon fraction (TUA) from a mature Alberta crude oil has been studied in detail. The predominating classes of compounds were found to be the acyclic isoprenoids, alkylcyclohexanes and alkylmethylcyclohexanes. Simulation experiments indicated that the alkylcyclohexanes and the alkylmethylcyclohexanes may have been formed by the advanced diagenesis of biologically occurring fatty acids. 相似文献
12.
Sotnikov N. V. Antonova E. E. Riazantseva M. O. Ovchinnikov I. L. Rubinstein I. A. Barinova V. O. Mit’ S. K. 《Geomagnetism and Aeronomy》2019,59(6):651-659
Geomagnetism and Aeronomy - Variations in the spectra and pitch-angle distribution of relativistic electrons are studied for the large magnetic storm on December 19–22, 2015, during which the... 相似文献
13.
The subtraction of the signal intensities of the ion fragments m/e 149 and m/e 151 in the GLC-MS computer analysis of the saturated hydrocarbons of a fossil fuel, reveals the distribution of the 5α and 5β steranes. This technique is a convenient method of establishing the efficacity of the thiourea clathration step, and simplifies routine geochemical analysis. Subtraction of the signal intensities of the ion fragments m/e 218 and m/e 217 reveals the distribution of 14α and 14β sterane isomers, and is a further refinement in the study of geological steroids. 相似文献
14.
L. V. Tverskaya S. V. Balashov N. N. Vedenkin V. V. Ivanov T. A. Ivanova D. S. Karpenko S. G. Kochura I. A. Maksimov N. N. Pavlov I. A. Rubinstein M. V. Tel’tsov D. A. Trofimchuk V. I. Tulupov V. V. Khartov 《Geomagnetism and Aeronomy》2008,48(6):719-726
Increases in solar protons and variations in the electron and proton fluxes from the outer radiation belt are studied based on the GLONASS satellite measurements (the circular orbit at an altitude of ～20000 km with an inclination of ～65°) performed in December 2006. Indications in the channels, registered protons with energies of Ep = 3–70 MeV and electrons with energies of Ee > 0.04 and >0.8 MeV, are analyzed. The data on electrons with Ee = 0.8–1.2 MeV, measured on the Express-A3 geostationary satellite, are also presented. Before the strong magnetic storm of December 14 (|Dst|max = 146 nT), the maximum of the outer belt electrons with the energy >0.7 MeV was observed at L ～ 4.5. After the storm, the fluxes of these electrons increased by more than an order of magnitude as compared to the prestorm level, and the maximum of a “new” belt shifted to L < 4 (minimal L reached by the GLONASS orbit). Under quiet geomagnetic conditions, solar protons with the energies >3 MeV fill only high-latitude legs of the GLONASS orbit. During the strong magnetic storm of December 15, the boundary of proton penetration into the magnetosphere almost merged with the orbital maximum of the proton radiation belt. 相似文献
15.
Oscar M?ller Ricardo O.Foschi Juan P.Ascheri Marcelo Rubinstein Sergio Grossman 《地震工程与工程振动(英文版)》2015,14(2):315-328
Performance-based design in earthquake engineering is a structural optimization problem that has, as the objective, the determination of design parameters for the minimization of total costs, while at the same time satisfying minimum reliability levels for the specifi ed performance criteria. Total costs include those for construction and structural damage repairs, those associated with non-structural components and the social costs of economic losses, injuries and fatalities. This paper presents a general framework to approach this problem, using a numerical optimization strategy and incorporating the use of neural networks for the evaluation of dynamic responses and the reliability levels achieved for a given set of design parameters. The strategy is applied to an example of a three-story offi ce building. The results show the importance of considering the social costs, and the optimum failure probabilities when minimum reliability constraints are not taken into account. 相似文献