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1.
K. Natesan 《Oxidation of Metals》1988,30(1-2):53-83
Oxidation-sulfidation studies were conducted on sheet samples of nickel aluminide, containing 23.5 at. % Al, 0.5 at. % Hf, and 0.2 at. % B in an annealed condition and after preoxidation treatments. Continuous weight-change measurements were made by a thermogravimetric technique in exposure atmospheres of air, a low-
gas mixture, and low-
gas mixtures with several levels of sulfur. Detailed scanning electron microscopy (SEM), X-ray, and electron microprobe analyses of the corrosion product scale layers were performed. The air-exposed specimens developed predominantly nickel oxide; the specimen exposed to a low-
. 相似文献
2.
High-temperature oxidation and sulfidation studies were conducted on an oxide-dispersion-strengthened alloy of composition Fe-20Cr-16Ni-4Al-1Y2O3. The oxidation studies were conducted in air and low-PO2 environments over a temperature range of 650–1200°C. Results are also reported on the sulfidation resistance of preformed oxide scales and the influence of reoxidation of preformed sulfide scales. Detailed microstructural results and x-ray diffraction analysis data are presented to substantiate the corrosion behavior of the alloy over the wide range of conditions anticipated in fossil-energy systems. Data are also presented on the corrosion behavior of the alloy in oxygen/sulfur mixed gas atmospheres, and the results are used to compare the corrosion behavior of the present alloy with other chromia- and alumina-forming alloys. 相似文献
3.
Jayaraman J. Thiagarajan Karthikeyan Natesan Ramamurthy Andreas Spanias 《Digital Signal Processing》2013,23(1):9-18
Mixing matrix estimation in instantaneous blind source separation (BSS) can be performed by exploiting the sparsity and disjoint orthogonality of source signals. As a result, approaches for estimating the unknown mixing process typically employ clustering algorithms on the mixtures in a parametric domain, where the signals can be sparsely represented. In this paper, we propose two algorithms to perform discriminative clustering of the mixture signals for estimating the mixing matrix. For the case of overdetermined BSS, we develop an algorithm to perform linear discriminant analysis based on similarity measures and combine it with K-hyperline clustering. Furthermore, we propose to perform discriminative clustering in a high-dimensional feature space obtained by an implicit mapping, using the kernel trick, for the case of underdetermined source separation. Using simulations on synthetic data, we demonstrate the improvements in mixing matrix estimation performance obtained using the proposed algorithms in comparison to other clustering methods. Finally we perform mixing matrix estimation from speech mixtures, by clustering single source points in the time-frequency domain, and show that the proposed algorithms achieve higher signal to interference ratio when compared to other baseline algorithms. 相似文献
4.
In this paper, we propose a numerical scheme which is almost second-order spatial accurate for a one-dimensional singularly perturbed parabolic convection-diffusion problem exhibiting a regular boundary layer. The proposed numerical scheme consists of classical backward-Euler method for the time discretization and a hybrid finite difference scheme for the spatial discretization. We analyze the scheme on a piecewise-uniform Shishkin mesh for the spatial discretization to establish uniform convergence with respect to the perturbation parameter. Numerical results are presented to validate the theoretical results. 相似文献
5.
This paper deals with the study of a post-processing technique for one-dimensional singularly perturbed parabolic convection–diffusion
problems exhibiting a regular boundary layer. For discretizing the time derivative, we use the classical backward-Euler method
and for the spatial discretization the simple upwind scheme is used on a piecewise-uniform Shishkin mesh. We show that the
use of Richardson extrapolation technique improves the ε-uniform accuracy of simple upwinding in the discrete supremum norm from O (N
−1 ln N + Δt) to O (N
−2 ln2
N + Δt
2), where N is the number of mesh-intervals in the spatial direction and Δt is the step size in the temporal direction. The theoretical result is also verified computationally by applying the proposed
technique on two test examples. 相似文献
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10.
Natesan Baskaran Hua Chang 《Journal of Materials Science: Materials in Electronics》2001,12(9):527-531
Thermo-Raman and dielectric constant measurements were carried out on the samples Ba(SnxTi1-x)O3, p obtained from the DTRI thermogram was found to be equal to the ferroelectric transformation temperature Tm, obtained from the maximum of the dielectric constant. Both Tp and Tm decreased almost linearly with increasing Sn concentrations. The Curie temperature Tc, Curie–Weiss constant Cw, Curie–Weiss-like constant C and the critical exponent obtained from the analysis of dielectric constant data clearly suggest that the ferroelectric to paraelectric phase transformation undergoes a crossover from sharp to diffuse phase transformation for Sn concentrations in the range from 0.05 to 0.1. © 2001 Kluwer Academic Publishers 相似文献