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51.
The problem of multidimensional scaling with city-block distances in the embedding space is reduced to a two level optimization
problem consisting of a combinatorial problem at the upper level and a quadratic programming problem at the lower level. A
hybrid method is proposed combining randomized search for the upper level problem with a standard quadratic programming algorithm
for the lower level problem. Several algorithms for the combinatorial problem have been tested and an evolutionary global
search algorithm has been proved most suitable. An experimental code of the proposed hybrid multidimensional scaling algorithm
is developed and tested using several test problems of two- and three-dimensional scaling. 相似文献
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Julius Meyer 《欧洲无机化学杂志》1902,35(4):3952-3957
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Franz Weitzer Masaaki Naka Nataliya Krendelsberger Frank Stein Cuiyun He Yong Du Julius C. Schuster Prof. Dr. 《无机化学与普通化学杂志》2010,636(6):982-990
The constitution of the ternary system Ni/Si/Ti is investigated over the entire composition range using X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), differential thermal analysis (DTA), and metallography. The solid state phase equilibria are determined for 900 °C. Eight ternary phases are found to be stable. The crystal structures for the phases τ1NiSiTi, τ2Ni4Si7Ti4, τ3Ni40Si31Ti13, τ4Ni17Si7Ti6, and τ5Ni3SiTi2 are corroborated. For the remaining phases the compositions are determined as Ni6Si41Ti53 (τ6), Ni16Si42Ti42(τ7), and Ni12Si45Ti43 (τ8). The reaction scheme linking the solid state equilibria with the liquidus surface is amended to account for these newly observed phases. The discrepancies between previous experimental conclusions and modeling results are addressed. The liquidus surface is dominated by the primary crystallisation field of τ1NiSiTi, the only congruently melting phase. 相似文献
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We consider a measure of dependence for symmetric α-stable random vectors, which was introduced by the second author in 1976. We demonstrate that this measure of dependence, which we suggest to call the spectral covariance, can be extended to random vectors in the domain of normal attraction of general stable vectors. We investigate the asymptotic of the spectral covariance function for linear stable (Ornstein–Uhlenbeck, log-fractional, linear-fractional) processes with infinite variance and show that, in comparison with the results on the properties of codifference of these processes, obtained two decades ago, the results for the spectral variance are obtained under more general conditions and calculations are simpler. 相似文献
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