We determine when the Hopf vector fields on orientable real hypersurfaces (M, g) in complex space forms are minimal or harmonic. Furthermore, we determine when these vector fields give rise to harmonic maps from (M, g) to the unit tangent sphere bundle (T1M, gS). In particular, we consider the special case of Hopf hypersurfaces and of ruled hypersurfaces. The Hopf vector fields on Hopf hypersur...

Audio signal source separation is an interesting task performed by humans. In this paper, we present a frequency grouping algorithm based on principles of harmonicity and dynamics: frequency components with a harmonic relation and similar dynamics belong to the same source. The grouping is demonstrated for a variety of sound mixtures.

Speech dereverberation is desirable in applications such as robust automatic speech recognition (ASR) in the real world. Although a number of dereverberation methods have been exploited, dereverberation is still a challenging problem especially when using a single microphone. To overcome this problem, a harmonicity based dereverberation method (HERB) has recently been proposed. HERB can blindly...

In this paper, instantaneous frequency amplitude spectrum (IFAS)-based fundamental frequency estimator is evaluated with speech signal corrupted by additive white gaussian noise. A key idea of the IFAS-based estimator is the use of degree of regularity of periodicity in spectrum of speech signal, defined by a quantity called harmonicity measure, for band selection in the fundamental frequency e...

We demonstrate the existence of exact discrete compact breather solutions in nonlinear Klein-Gordon systems, and complete the work of Tchofo Dinda and Remoissenet [Phys. Rev. E 60, 6218 (1999)], by showing that the breathers stability is related principally to the lattice boundary conditions, the coupling term, and the harmonicity parameter.

The theory of minimal surfaces and more generally of minimal immersions is one of the most fashionable branches in Diierential Geometry. Since the very early stage of the theory it was clear that there was a strong link between minimality and harmonicity. From a relation of E. Beltrami 4] follows that a surface in R 3 is minimal if and only if the components of the position vector are harmonic ...