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31.
M. D. Joseph Sebastian B. Rudraswamy M. C. Radhakrishna Ramani 《Bulletin of Materials Science》2003,26(5):509-515
Cobalt ferrite (CoxFe3?xO4) is prepared in powder form by thermal decomposition of iron and cobalt salts and is analysed by X-ray diffraction and Mössbauer spectroscopic techniques. The variation of Mössbauer parameters, lattice parameters and crystallite size of the products formed with variation in the composition of Fe and Co ratios are studied. The studies confirm the formation of nano-size cobalt ferrite particles with defect structure and it is found to be maximum for the Fe : Co = 60 : 40 ratio of the initial precursor oxides. 相似文献
32.
综述了粉末冶金温压工艺的研究进展,概述了温压工艺的粉末原料、聚合物、温度、压力、烧结环节对温压工艺的影响和温压工艺的致密化机理。详细介绍了温压工艺的新进展—流动温压、高压温压等,并对其应用前景进行了展望。 相似文献
33.
In this paper we propose a new method to estimate parameters of a dynamical system from observation data on the basis of a neural network collocation method. We construct an object function consisting of squared residuals of dynamical model equations at collocation points and squared deviations of the observations from their corresponding computed values. The neural network is then trained by optimizing the object function.The proposed method is demonstrated by performing several numerical experiments for the optimal estimates of parameters for two different nonlinear systems. Firstly, we consider the weakly and highly nonlinear cases of the Lorenz model and apply the method to estimate the optimum values of parameters for the two cases under various conditions. Then we apply it to estimate the parameters of one-dimensional oscillator with nonlinear damping and restoring terms representing the nonlinear ship roll motion under various conditions. Satisfactory results have been obtained for both the problems. 相似文献
34.
粉末冶金低合金钢的制备和性能研究进展 总被引:1,自引:0,他引:1
从粉末制备、成形工艺、烧结工艺和组织控制等方面,系统的介绍了国内外粉末冶金低合金钢的制备技术,并对其研究方向和应用前景进行了展望。 相似文献
35.
Tracking characteristics on unstructured meshes is an important part of many numerical methods in computational fluid mechanics.
In this paper, we propose an efficient algorithm for characteristic tracking on two-dimensional unstructured triangular meshes.
Numerical experiments, including an example for applying this algorithm with the Eulerian-Lagrangian localized adjoint method
(ELLAM) to solve a convection-dominated convection-diffusion problem, are presented to demonstrate the efficiency of this
algorithm. 相似文献
36.
Michael W. Anderson 《Topics in Catalysis》1996,3(1-2):195-220
The power of solid-state NMR for the interrogation of porous catalytic materials is illustrated using three examples. First,
for the investigation of catalytic processes occurring within the confines of a microporous catalyst NMR is shown to reveal
both the details of shape-selectivity and the nature of internal surface species. Second, NMR is shown to be a powerful short-range
tool to reveal precise structural information on highly disordered microporous titanosilicates. Despite long-range disorder
the short-range order is maintained and can be easily studied. Finally, the same utility of probing short-range chemical phenomena
is shown to be crucial for the investigation of novel-ordered-amorphous-mesoporous materials known generically as M41S. This
class of material is currently one of the most important with potential catalytic application. 相似文献
37.
38.
The residual intergranular strains in textured Zircaloy-2 plate samples induced by cooling from 823 K to ambient temperatures, by cold-rolling by 1.5% and 25% and by deforming in tension by 1.5% were measured by neutron diffraction. The strong rolling texture, which gives rise to two ideal orientations, permitted the interpretation of much of the data in terms of strain tensors for the two orientations. The experimental results were compared with calculations based on the elasto-plastic self-consistent model with no adjustable parameters. Close agreement was obtained for samples in the as-cooled state and deformation in tension by 1.5% but the agreement is less satisfactory for cold-rolling. 相似文献
39.
D. Helary O. Dugne X. Bourrat P.H. Jouneau F. Cellier 《Journal of Nuclear Materials》2006,350(3):332-335
Electron back-scattering diffraction (EBSD) can be successfully performed on SiC coatings for HTR fuel particles. EBSD grain maps obtained from thick and thin unirradiated samples are presented, along with pole figures showing textures and a chart showing the distribution of grain aspect ratios. This information is of great interest, and contributes to improving the process parameters and ensuring the reproducibility of coatings. 相似文献
40.
The Fe-Cu system is of relevance to the nuclear industry because of the deleterious consequences of Cu precipitates in the mechanical properties of Fe. Several sets of classical potentials are used in molecular dynamics simulations studies of this system, in particular that proposed by Ludwig et al. [M. Ludwig, D. Farkas, D. Pedraza, S. Schmauder, Model. Simul. Mater. Sci. Eng. 6 (1998) 19]. In this work we extract thermodynamic information from this interatomic potential. We obtain equilibrium phase diagram and find a reasonable agreement with the experimental phases in the regions of relevance to radiation damage studies. We compare the results with the predicted phase diagram based on other potential, as calculated in previous work. We discuss the disagreements found between the phase diagram calculated here and experimental results, focusing on the pure components and discuss the applicability of these potentials. Improved potentials, primarily for the pure components, should be developed to account for proper phase stability in the solid phase up to melting. Finally we suggest an approach to improve existing potentials for this system. 相似文献