The possibility to achieve focusing in a three-layer cylindrical biological tissue model, by using concentrically placed TEM waveguide applicators excited by short baseband pulses, is examined rigorously. The medium response ...

A classical theorem due to Young states that the cosine polynomial c n(x) = 1 + ∑k=1n cos(kx)/k is positive for all n ≥ 1 and x ∈ (0, π). We prove the following refinement. For all n ≥ 2 and x ∈ [0, π] we have 1/6 + c(π - ...

We introduce the concept of local dyadic stationarity, to account for nonstationary time series, within the framework of Walsh-Fourier analysis. We define and study time-varying, dyadic, autoregressive, moving average ...

We establish sharp lower and upper estimates for the cosine sums Equation Presented. We also discuss the possibility of extending these results to other cosine sums of this type.

We consider the estimation of a density function on the basis of a random sample from a weighted distribution. We propose linear and nonlinear wavelet density estimators, and provide their asymptotic formulae for mean ...