Sn(II)1.2(Nb(V)1.6Sn(IV)0.4)O6 pyrochlore precursor was oxidized at temperature of the range 573–973 K in 1% O2/Ar and O2 gases for various periods of time. Two kinds of novel metastable phases with a composition of Sn(IV)0.6(Nb(V)0.8Sn(IV)0.2)O3.6 could be synthesized. Further, the other novel metastable phase with the same composition was found as a phase contained. One of the metastable phases was the cubic κ-CeZrO4 related-type possessing the fluorite-related structure, which was formed by the cation diffusionless insertion of the oxygen atom into original oxygen vacant site of the pyrochlore-type structure. Another was an orthorhombic α-PbO2 related-type possessing a cation ordered arrangement unlike a well known NiWO4 structure. The other was the rutile related-type possessing a cation ordered arrangement. Appearance of the two latter metastable phases could be attributed to the displacement of the oxygen stacking in the κ-CeZrO4 related-type phase without cation redistributions. The appearance mechanisms were analogous to the well known transformations for AX2 compounds among rutile-type, α-PbO2-type, and fluorite-type phases under high pressure and its release. The dependence of the appearance of these novel metastable phases on oxygen partial pressure and temperature has been discussed in terms of the driving forces and energy barriers for reactions. 相似文献
During stamping-die design, the formability in sheet-metal forming process has been evaluated by the geometrical functions in ‘Die-Face CAD’, which has been developed and improved by Toyota Motor Corporation. When evaluation by these functions is difficult, formability has been estimated by performing experiments using test dies in which the forming defects are similar to those in the actual process.
A numerical method has been developed in order to substitute numerical analysis for experiments using test dies for the accurate prediction of defects in sheet-metal forming. The elastic-plastic FEM with the commercial code ‘JNIKE3D’ has been improved in the areas of: (1) the material constitutive equation; (2) the consideration of the pressure distribution on the blank-holder; and (3) the evaluation of breakage initiation. Using the improved method, the square-cup drawing process and the hemming process have been analyzed. Numerical results for strain, breakage initiation, and hemming deflection were in good agreement with experimental results. The formability of laser-welded blanks and the most efficient process to form them were evaluated also using the improved method. 相似文献
This paper discusses the breaking ability of an air blast circuit breaker (ABB) or SF6 gas circuit breaker (GCB), and the interrupting phenomena around current zero in the case where a resistor or capacitor is connected in parallel with its interrupter to improve the breaking ability. It has been clarified that the use of a parallel resistor for ABB, and that of a parallel capacitor for GCB are the most effective methods to improve the breaking abilities; the parallel resistor not only serves to reduce the rate of rise of the transient recovery voltage (rrrV), but also shifts the current from the interrupter to itself around the current zero, thus reducing the stress for interruption. The improvement of the breaking ability is achieved by reducing the initial average rrrV between zero and 1 microseconds (inherent value), when the parallel capacitor is used with the GCB. 相似文献
The characteristic fatigue behavior of carburized and quenched steel with internal oxides and non-martensitic microstructure near the surface was presented through rotating bending fatigue test. The S-N diagram revealed two knees and the specimens continued to fail over 107 stress cycles. The fatigue limit could not be obtained even at 108 stress cycles. The test results were compared to those for the specimens without surface structure anomalies to show the effect of structure anomalies on the fatigue behavior of carburized steel. 相似文献
Lung from male and female rats fasted for 4 days were used. Phospholipid, phosphatidylcholine and its molecular species were
analyzed in lungs from these rats and effects of fasting upon the biosynthesis of phosphatidylcholine in lungs from both sexes
were determined using radioactive choline. The molecular species of phosphatidylcholine in both male and female rats did not
differ with fasting except the monoenoic species. Incorporation of choline into phosphatidylcholine in both male and female
rats significantly increased after fasting, but distribution of radioactivity in phosphatidylcholine yielded similar values
in each group. These results suggest that the decrease of saturated phosphatidylcholine content after fasting may be not due
to specific change in saturated phosphatidylcholine. 相似文献
Changing the partial pressure of sulfur Ps2 at temperatures of 750° and 950°C, phase equilibria on the Mo-S system by solid-gas reaction were investigated. Hexagonal 2H-MoS2 and monoclinic Mo2S3 phases were identified from the x-ray powder diffraction pattern. The 2H-MoS2 had a slight homogeneity range, i.e. MoS1.978 to MoS2.0 at 950°C, MoS1.983 to MoS2.0 at 750°C. No remarkable variation of lattice parameters for the MoS2 was observed. The composition of the Mo2S3 phase was not stoichiometric MoS1.5 but MoS1.457 at 950°C. At 750°C the composition of the Mo2S3 phase could not be determined since it was quite difficult to establish the equilibrium state between the gas and the condensed phases. This finding agreed well with the result of Morimoto and Kullerud. 相似文献
Variation in illumination conditions caused by weather, time of day, etc., makes the task difficult when building video surveillance systems of real world scenes. Especially, cast shadows produce troublesome effects, typically for object tracking from a fixed viewpoint, since it yields appearance variations of objects depending on whether they are inside or outside the shadow. In this paper, we handle such appearance variations by removing shadows in the image sequence. This can be considered as a preprocessing stage which leads to robust video surveillance. To achieve this, we propose a framework based on the idea of intrinsic images. Unlike previous methods of deriving intrinsic images, we derive time-varying reflectance images and corresponding illumination images from a sequence of images instead of assuming a single reflectance image. Using obtained illumination images, we normalize the input image sequence in terms of incident lighting distribution to eliminate shadowing effects. We also propose an illumination normalization scheme which can potentially run in real time, utilizing the illumination eigenspace, which captures the illumination variation due to weather, time of day, etc., and a shadow interpolation method based on shadow hulls. This paper describes the theory of the framework with simulation results and shows its effectiveness with object tracking results on real scene data sets. 相似文献
We have developed a novel pulse-coupled neural network (PCNN) for speech recognition. One of the advantages of the PCNN is
in its biologically based neural dynamic structure using feedback connections. To recall the memorized pattern, a radial basis
function (RBF) is incorporated into the proposed PCNN. Simulation results show that the PCNN with a RBF can be useful for
phoneme recognition.
This work was presented in part at the 7th International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18,
2002 相似文献
High temperature corrosion tests in 80 pct Na2SO4-20 pct NaCI were made on five Fe-30 wt pct Cr-5 wt pct Al alloys containing various amounts of cerium up to 0.68 pct. After the corrosion tests, samples were examined metallographically and by X-ray diffraction and X-ray microanalysis. It was found that the surface scale formed on each sample decreased in thickness as the Ce content increased. Electron probe microanalyses suggest that this retarding behavior is related to the early formation of a Ce-induced protective scale of α-Al2O3. The role of Ce in promoting the formation of the α-Al2O3 scale is discussed. 相似文献