We study fracture of notched samples made of quasi-brittle, polyphase materials like rock, concrete or ceramics. The fracture demonstrates the size effect during loading. This means that a full-size sample made of such a material exhibits different fracture behaviour than a laboratory-size sample. The effect is explained by the existence of an extended zone of distributed defects and cracks (pr...

The fast growth of wireless applications in recent years has driven intense efforts to design highly integrated, high-performance, low-cost RFICs. Both low-IF [33]-[37] and double-quadrature [38]-[40] architectures have been adopted as promising receiver topologies to realize these design goals because they combine the advantages of heterodyne and direct-conversion architectures. In the low-IF ...

A general expression for the distortion rate function (DRF) of cyclostationary Gaussian processes in terms of their spectral properties is derived. This expression can be seen as the result of orthogonalization over the different components in the polyphase decomposition of the process. We use this expression to derive, in a closed form, the DRF of several cyclostationary processes arising in p...

In this paper we connect the design of biorthogonal modulated filter banks with the idea of lifting schemes, which were proposed for the construction of biorthogonal wavelets. Based on this formulation, we derive a lattice-like structure for the polyphase components. As the rotationbased structures for the design and implementation of paraunitary modulated filter banks, our structure automatica...

Wavelets have proved particularly effective for extracting discriminative features in ECG signal classification. In this paper, we show that wavelet performances in terms of classification accuracy can be pushed further by customizing them for the considered classification task. A novel approach for generating the wavelet that best represents the ECG beats in terms of discrimination capability ...

The main purpose of the paper is to summarize some fundamental results concerning the matrix impulsive differential equations with impulses at fixed points. The theory of impulsive matrix differential equations is interesting in itself and it will assume greater importance in the near future, since the application of the theory to various fields of science is also increasing, especially in the ...