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排序方式: 共有87条查询结果,搜索用时 31 毫秒
1.
We consider a shock-type wave solution of the modified quintic complex Ginzburg-Landau equation and make a numerical study
of its spatiotemporal stability. Discussions related to the behavior of this front wave are introduced and it is shown how
the velocities of the wave can be used to collect information concerning the pattern formation in the system.
Published in Neliniini Kolyvannya, Vol. 10, No. 2, pp. 270–276, April–June, 2007. 相似文献
2.
Product integration rules generalizing the Fej?r, Clenshaw-Curtis,and Filippi quadrature rules respectively are derived for integralswith trigonometric and hyperbolic weight factors. The Chebyshevmoments of the weight functions are found to be given by well-conditionedexpressions, in terms of hypergeometric functions 0F1. An a priori error estimator is discussed which is shown bothto avoid wasteful invocation of the integration rule and toincrease significantly the robustness of the automatic quadratureprocedure. Then, specializing to extended Clenshaw-Curtis (ECC) rules,three types of a posteriori error estimates are considered andthe existence of a great risk of their failure is demonstratedby large scale validation tests. An empirical error estimator,superseding them for slowly varying integrands, is found toresult in a spectacular increase in the output reliability. Finally, enhancements in the control of the interval subdivisionstrategy aiming at increasing code robustness is discussed.Comparison with the code DQAWO of QUADPACK, with about a hundredthousand solved integrals, is illustrative of the increasedrobustness and error estimate reliability of our computer codeimplementation of the ECC rules. 相似文献
3.
Ion chromatography was used to determine trace anionic contamination on the surface of hard disk drive components. These contaminants can have a detrimental effect on device reliability and yield. Disk drive components were soaked in deionized water and these extracts were analyzed for anions. The anions fluoride, acetate, formate, acrylate, methacrylate, chloride, nitrite, bromide, nitrate, benzoate, sulfate, oxalate, phthalate and phosphate were separated on a high-performance anion-exchange column and determined at concentrations less than 1 microg/l with suppressed conductivity detection. The extract solutions were analyzed either by injecting 1 ml or by preconcentrating 5 ml. We evaluated the performance of both methods. 相似文献
4.
The tin-collection scheme of fire-assaying has been simplified to permit the rapid and accurate determination of platinum, palladium and gold in ores and related materials. The presence of tellurium in the charge ensures that the precious metals remain insoluble during the parting of the tin button with hydrochloric acid. The residue is easily collected and dissolved and the resultant solution analysed for the precious metals by AAS. The accuracy of the method has been established by application to five diverse certified reference materials. 相似文献
5.
We have evaluated the efficiency of a fast, simple and efficient method, fluorophore-assisted carbohydrate electrophoresis (FACE), for the characterization of plant N-linked glycans. After their enzymatic release from plant glycoproteins, N-glycans were reductively aminated to the charged fluorophore 8-aminonaphthalene-1, 3, 6-trisulfonic acid (ANTS) and separated using high resolution polyacrylamide gel electrophoresis. In addition, an affinity purification procedure using concanavalin A was developed for separation of ANTS-labeled high-mannose-type N-glycans from other plant oligosaccharides. 相似文献
6.
We prove the existence of fast traveling pulse solutions in excitable media with non-local coupling. Existence results had been known, until now, in the case of local, diffusive coupling and in the case of a discrete medium, with finite-range, non-local coupling. Our approach replaces methods from geometric singular perturbation theory, that had been crucial in previous existence proofs, by a PDE oriented approach, relying on exponential weights, Fredholm theory, and commutator estimates. 相似文献
7.
The infrared absorption of the ν3 band region of SF6, at temperatures spanning the 130 to 297 K range, has been reexamined using improved instrumentation with one goal: to estimate the broadening of parameters by nitrogen gas. These parameters are compared to previous literature predictions and an extended set of IR cross-sections is proposed and compared to other existing datasets. 相似文献
8.
Adams B Lowpetch K Thorndycroft F Whyte SM Young DW 《Organic & biomolecular chemistry》2005,3(18):3357-3364
Two members of the alpha-family of PLP-dependent enzymes, L-aspartate aminotransferase and D-amino acid aminotransferase, have been shown to catalyse beta-substitution of L- and D-beta-chloroalanine respectively with beta-mercaptoethanol, reactions typical of the beta-family of PLP-dependent enzymes. The reaction catalysed by L-aspartate aminotransferase has been shown to occur with retention of stereochemistry, a typical outcome for reactions catalysed by beta-family enzymes. There are also indications that the reaction catalysed by D-amino acid aminotransferase may involve retention of stereochemistry. Both enzymes have been shown to catalyse exchange at C-3 when the appropriate enantiomer of beta-chloroalanine is the substrate. 相似文献
9.
BAGHERI GH Azar 《中国化学》2009,27(6):1073-1078
The complexation of zinc(II) with dopamine has been investigated by spectrophotometric measurements in mixed solvent system at an ionic strength of 0.2 mol•dm-3 sodium chloride, employed at at (15±0.1), (25±0.1), (35±0.1) ℃ at inin a pH range of ca. 6 to ca. 7 with a high ratio of ligand to metal. The effect of solvent systems on protonation and complexation are was was discussed. Linear relationships are werewere observed by plotting lg K versus 1/D, where K and D show stability and dielectric constants, respectively. 相似文献
10.
We give a complete characterization of constant quadratic functions over an affine variety. This result is used to convexify
the objective function of a general quadratic programming problem (Pb) which contains linear equality constraints. Thanks
to this convexification, we show that one can express as a semidefinite program the dual of the partial Lagrangian relaxation
of (Pb) where the linear constraints are not relaxed. We apply these results by comparing two semidefinite relaxations made
from two sets of null quadratic functions over an affine variety.
相似文献