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
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
In our real-world applications, data may be imprecise in which levels or degrees of preciseness of data are intuitively different. In this case, fuzzy set expressions are considered as an alternative to represent the imprecise data. In general, the degree of similarity relationship between two fuzzy (imprecise) data in real-world applications may not necessarily be symmetric or transitive. In order to provide such a degree of similarity between two fuzzy data, we introduced the fuzzy conditional probability relation. The concept of a fuzzy conditional probability relation may be considered as a concrete example of weak similarity relation which in turn is a special type of fuzzy binary relation generalizing similarity relation. Two important applications concerning the application of Knowledge Discovery and Data Mining (KDD) in the presence of a fuzzy data table (usually called fuzzy information system), namely removing redundant objects and recognizing partial or total dependency of (domain) attributes, are considered induced by the fuzzy conditional probability relation. Here, the fuzzy information system contains precise as well as imprecise data (fuzzy values) about objects of interest characterized by some attributes. Related to the dependency of attributes, we introduce the fuzzy functional dependency that satisfies Armstrongs Axioms. In addition, we also discuss some interesting applications such as approximate data reduction and projection, approximate data querying and approximate joining in order to extend the query system. 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
The standard Gibbs energies of formation of Fe2Mo3O12, Fe2Mo3O8, FeMoO4, and Fe2MoO4 of the Fe-Mo-O ternary system and the μ phase of the Fe-Mo binary system have been determined by measuring electromotive forces of galvanic cells having an Y2O3-stabilized ZrO2 solid electrolyte. The results are as follows: $$\begin{gathered} \Delta _f G^\circ (FeMoO_4 )/kJ \cdot mol^{ - 1} = - 1053.5 + 0.2983(T/K) \pm 0.4 \hfill \\ Temperature range: 1112 to 1339 K \hfill \\ \Delta _f G^\circ (Fe_2 Mo_3 O_8 )/kJ \cdot mol^{ - 1} = - 2347 + 0.6814(T/K) \pm 1 \hfill \\ Temperature range: 1112 to 1339 K \hfill \\ \Delta _f G^\circ (Fe_2 Mo_3 O_{12} )/kJ \cdot mol^{ - 1} = - 2993 + 0.9105(T/K) \pm 2 \hfill \\ Temperature range: 1040 to 1145 K \hfill \\ \Delta _f G^\circ (Fe_{0.58} Mo_{0.42} )/kJ \cdot mol^{ - 1} = - 18.7 + 0.0117(T/K) \pm 0.1 \hfill \\ Temperature range: 1162 to 1223 K \hfill \\ \Delta _f G^\circ (Fe_2 MoO_4 )/kJ \cdot mol^{ - 1} = - 1174 + 0.342(T/K) \pm 1 \hfill \\ Temperature range: 1243 to 1466 K \hfill \\ \end{gathered} $$ where the standard pressure is 1 bar (100 kPa). 相似文献