Hideyuki Imai

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The aim of "blind source separation" is to recover mutually independent unknown source signals from observations obtained through an unknown linear mixture system. Simultaneous diagonalization of correlation matrices (second-order statistics) of observations is one of the resolutions, when the unknown source signals are non-stationary. Although it is(More)
Four species of the fish genus Pempheris are recognized for the Red Sea: P. adusta Bleeker, 1877; P. mangula Cuvier, 1829; P. nesogallica Cuvier in Cuvier & Valenciennes, 1831; and a new species P. tominagai. All are wide-ranging in the western Indian Ocean, and P. mangula has migrated via the Suez Canal to the eastern Mediterranean Sea. Morphological and(More)
The bigfin reef squid Sepioteuthis lessoniana Férussac, 1831 in Lesson (1830–1831) is widely distributed in the Indo-Pacific, where it is a very valuable fishery resource (Dunning, 1998). Thus, a lot of ecological research of this species were reported (e.g. Ikeda, 1933; Choe & Ohshima, 1961; Segawa, 1987; Ueta, 2003; Ikeda et al., 2009). Segawa et al.(More)
The pronghorn spiny lobster, Panulirus penicillatus, is a circumtropical species which has the widest global distribution among all the species of spiny lobster, ranging throughout the entire Indo-Pacific region. Partial nucleotide sequences of mitochondrial DNA COI (1,142-1,207 bp) and 16S rDNA (535-546 bp) regions were determined for adult and phyllosoma(More)
A novel approach for k-nearest neighbor (k-NN) searching with Euclidean metric is described. It is well known that many sophisticated algorithms cannot beat the brute-force algorithm when the dimensionality is high. In this study, a probably correct approach, in which the correct set of k-nearest neighbors is obtained in high probability, is proposed for(More)
The pronghorn spiny lobster Panulirus penicillatus is a highly valuable species which is widely distributed in Indo-West Pacific and Eastern Pacific regions. Mitochondrial DNA control region sequences (566-571 bp) were determined to investigate the population genetic structure of this species in the Indian Ocean. In total, 236 adult individuals of Panulirus(More)
To identify lobster phyllosoma larvae of the genus Panulirus occurring in waters adjacent to Japan, genetic variation within and between 10 Indo-Pacific lobster species was investigated using restriction fragment length polymorphism (RFLP) analysis for the 1300-base pair mitochondrial cytochrome oxidase I (COI) gene. RFLP analysis using two endonucleases(More)
A perfect reconstruction of functions in a reproducing kernel Hilbert space from a given set of sampling points is discussed. A necessary and sufficient condition for the corresponding reproducing kernel and the given set of sampling points to perfectly recover the functions is obtained in this paper. The key idea of our work is adopting the reproducing(More)
In multivariate statistical methods, it is important to identify influential observations for a reasonable interpretation of the data structure. In this paper, we propose a method for identifying influential data in the fuzzy C-means (FCM) algorithm. To investigate such data, we consider a perturbation of the data points and evaluate the effect of a(More)