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1.
Various tests have been carried out in order to compare the performances of several methods used to solve the non-symmetric linear systems of equations arising from implicit discretizations of CFD problems, namely the scalar advection-diffusion equation and the compressible Euler equations. The iterative schemes under consideration belong to three families of algorithms: relaxation (Jacobi and Gauss-Seidel), gradient and Newton methods. Two gradient methods have been selected: a Krylov subspace iteration method (GMRES) and a non-symmetric extension of the conjugate gradient method (CGS). Finally, a quasi-Newton method has also been considered (Broyden). The aim of this paper is to provide indications of which appears to be the most adequate method according to the particular circumstances as well as to discuss the implementation aspects of each scheme. 相似文献
2.
3.
化学光谱法测定5N氧化钆中14个稀土杂质元素 总被引:2,自引:0,他引:2
报道了化学光谱法测定5N高纯氧化钆中14个稀土杂质元素,在P507萃淋树脂色层柱上分离氧化钆中稀土杂质元素,分别采用定量分离La-Sm及Tb-Lu+Y和部份分离Eu的方法,并相应地采用碳粉吸附法和碳粉粉末法进行光谱测定。分离时间为3.5h,测定下限为1.2μg/g(RE)。 相似文献
4.
我们曾报道了一类新型双羟基键合固定相(GDSB)的合成,研究表明这类固定相具有键合相浓度高,热和化学稳定性好的特点,可用于性质相似的有机化合物的分离。 本文以GDSB为色谱柱填料,含Cu~(2+)离子和烷基磺酸盐的HAc-NaAc缓冲溶液作流动 相似文献
5.
本文用新方法合成了Cr(bza)_3,改进了其mer-、fac-异构体的分离方法;增大了Cr(acac)_3的化学拆分量(1.5g)。试制了DBT(二苯甲酰-d-酒石酸)吸附型手性固定相(CSP),并成功地用于色谱拆分标题配合物的对映体,mer-[Cr(bza)_3]的部分拆分是首次发现的,其他配合物的拆分结果均优于文献方法。根据mer-[Cr(bza)_3)拆分流出液前、后组分的CD光谱,指定了其对映体绝对构型。还讨论了DBT吸附型CSP的拆分效能和色谱特性。 相似文献
6.
S. V. Kurbatova E. E. Finkelshtein E. A. Kolosova A. V. Kartashev S. N. Yashkin 《Journal of Structural Chemistry》2004,45(1):144-150
The potential of the structural analogy method in the topological studies of adamantane derivatives and analogs is demonstrated. The topological and structural characteristics of these compounds are calculated. Chromatographic retention indices were determined experimentally. Correlations between the topological indices and the physicochemical and chromatographic characteristics are investigated. 相似文献
7.
Sumio Sakka 《Journal of Sol-Gel Science and Technology》1994,2(1-3):451-455
The present state of our knowledge on sol-gel coating films has been reviewed. A qualitative discussion is made on the limit of the film thickness which can be achieved in the sol-gel method and the factors affecting the film thickness. Considering that properties of the film are intimately related to the microstructure, types of microstructures accomplished by the sol-gel coating are introduced with examples. 相似文献
8.
Summary A program is described which calculates the number of effective plates and the coating efficiency over the entire range of a test chromatogram. The peak widths at half height are derived by assuming a Gaussian peak shape. The interpolated peak width at k=4 is used for computing a standardized number of effective plates. Plate height, column permeability, overall performance and a novel parameter called sampling efficiency are calculated from 5 other figures — i. e. carrier gas code, pressure drop, column length, column temperature and particle size.Dedicated to Dr. Leslie S. Ettre for his 60th birthday. 相似文献
9.
A strong chromatographic effect has been established during copper-managenese formate impregnation of γ-Al2O3. The samples obtained have been characterized by adsorption, IR, X-ray and magnetochemistry methods. 相似文献
10.
A rapid and reliable high performance liquid chromatographic (HPLC) method for the simultaneous determination of heterocyclic
compounds, namely nicotinic acid, nicotinamide, and 3-cyanopyridine, in industrial effluent is described. A Φ4.6 mm × 150
mm, 5 μm C-18 reversed phase stationery phase, and a methanol-acetonitrile-water tertiary mobile phase (20:20:60 v/v) were
used for separation. The detection wavelength of a diode array (DAD) was set at 216 nm with a bandwidth of 16 nm. Phenol was
used as an internal standard. The regression equations revealed a linear relationship between the concentration of the analytes
injected and the peak area detected by DAD. The limits of detection (S/N = 3) ranged from 0.70 to 1.18 mg L−1, the recoveries ranged from 87% to 102% and the precision expressed as % RSD intra-day and inter-day varied from 0.9 to 3.9
and 1.2 to 5.6, respectively. This method is rapid, sensitive and suitable for the monitoring of nicotinic acid, nicotinamide,
and 3-cyanopyridine in effluent of related pharmaceutical manufacturing plants. 相似文献