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91.
The development of a matured metallurgical process allows the reduction of the sulphur, nitrogen, hydrogen and total oxygen content to the lowest values in only one secondary metallurgical step during treatment in a ladle tank degassing unit. By careful adjustment of a lime-saturated ladle top slag at the beginning of the vacuum treatment, it is possible to obtain a desulphurization degree of more than 95%. The process of nitrogen removal by a stirring gas can be described with a dynamic model in excellent agreement with plant trials. The nitrogen content after vacuum treatment depends mainly on the nitrogen content before vacuum, the stirring gas quantity and the sulphur content. The achievable hydrogen contents mainly depend on the stirring gas quantity and dehydrogenisation can be described by the same model used for denitrogenisation. By a cleanliness stirring after the vacuum treatment under a nearly SiO2-free-, lime-alumina slag, saturated with lime, the total-oxygen content can be lowered to less than 20 ppm. 相似文献
92.
An optimized distribution of tilt angles for tomography of specimens of non-circular cross-section is derived and tested with reconstructions of a phantom model. 相似文献
93.
94.
Fathi Moussa Pascale Chretie Pierre Dubois Laurence Chuniaud Michelle Dessante Fran ois Trivin Pierre-Yves Sizaret Viatcheslav Agafonov Ren C olin Henri Szwarc Virginie Greugny Claude Fabre Andr Rassat 《Fullerenes, Nanotubes and Carbon Nanostructures》1995,3(3):333-342
In order to check its possible acute toxicity, C60 was incorporated into living human phagocytes. It was observed that C60 has no influence on the survival of human leukocytes. 相似文献
95.
Frdric Dufaux Iole Moccagatta Fabrice Moscheni Henri Nicolas 《Journal of Visual Communication and Image Representation》1994,5(4)
This paper proposes a segmentation of block-based motion fields under the constraint of the entropy criterion. The segmentation is performed by a vector quantization technique which associates the segmentation pattern to an element of a codebook. Optimization of the bit rate as a trade-off between motion and segmentation on the one hand and prediction error on the other hand is addressed. An estimation of the amount of information to code the displaced frame difference is derived, making it possible to control the segmentation process. Simulation results show the efficiency of the segmentation method combined with the entropy criterion in a video coding scheme. 相似文献
96.
This paper deals with relational databases which are extended in the sense that fuzzily known values are allowed for attributes. Precise as well as partial (imprecise, uncertain) knowledge concerning the value of the attributes are represented by means of [0,1]-valued possibility distributions in Zadeh's sense. Thus, we have to manipulate ordinary relations on Cartesian products of sets of fuzzy subsets rather than fuzzy relations. Besides, vague queries whose contents are also represented by possibility distributions can be taken into account. The basic operations of relational algebra, union, intersection, Cartesian product, projection, and selection are extended in order to deal with partial information and vague queries. Approximate equalities and inequalities modeled by fuzzy relations can also be taken into account in the selection operation. Then, the main features of a query language based on the extended relational algebra are presented. An illustrative example is provided. This approach, which enables a very general treatment of relational databases with fuzzy attribute values, makes an extensive use of dual possibility and necessity measures. 相似文献
97.
The grafting of a liquid acrylic derivative (2-methylenepentane-1,5-dicarboxylic acid diethylester) on the surface of a polyethylene film (HD) was carried out in the presence of benzoylperoxide. The wettability of the surface was investigated with respect to the adhesion properties against aluminium and compared with those of a film of polyethylene grafted in mass with acrylic acid. The mobility of the surface grafted chains may cause the differences in the observed comportment. 相似文献
98.
Henri Clergeot 《电信纪事》1984,39(3-4):113-128
Quadratic estimators of power spectra are compared, for a given total observation range, by using the matrix of the associated quadratic form. Considering the case of smooth spectra, it is shown that the smallest variance for a given resolution is achieved if this matrix is Toeplitz. From the estimation and the computation points of view, a detailed comparison is made between two types of estimation schemes. The first is composed of methods equivalent to the smoothing of a single periodogram; the second reduces to the very popular Welch method (averaging of several short, modified periodograms). Our presentation makes clear the choice of parameters and should prevent errors, common mainly when dealing with short records. 相似文献
99.
100.