In this article, we investigate the application of wavelet packet transform as a novel spectrum sensing approach. The main attraction for wavelet packets is the tradeoffs they offer in terms of satisfying various performance metrics such as frequency resolution, variance of the estimated power spectral density (PSD) and complexity. The results of the experiments show that the wavelet based appr...

Information Retrieval (IR) systems combine a variety of techniques stemming from logical, vector-space and probabilistic models. This variety of combinations has produced a significant increase in retrieval effectiveness since early 1990s. Nevertheless, the quest for new frameworks has not been less intense than the research in the optimization and experimentation of the most common retrieval m...

We study the physical limitations placed on CMB temperature and polarization measurements of the initial power spectrum by geometric projection, acoustic physics, gravitational lensing and the joint fitting of cosmological parameters. Detailed information on the spectrum is greatly assisted by polarization information and localized to the acoustic regime k = 0.02 − 0.2 Mpc with a fundamental re...

We report the first Fourier domain modelocked (FDML) laser constructed using optical parametric amplifier (OPA) in conjunction with an erbium-doped fiber amplifier (EDFA), centered at approximately 1555 nm, to the best of our knowledge. We utilize a one-pump OPA and a C-band EDFA in serial configuration with a tunable Fabry-Perot interferometer to generate a hybrid FDML spectrum. Results demons...

In this work, we have reformulated the selection of a few responding units tuned to patterns of activity from the Fourier spectrum as a multilayer system composed of four stages of di erent kinds of feature detectors. The system output is a sparse representation for images that produces an organization according to object power discrimination. The resultant multilayer system provides a more e c...

The extremal Fourier intensities are studied for stationary Edwards-Wilkinson-type, Gaussian, interfaces with power-law dispersion. We calculate the probability distribution of the maximal intensity and find that, generically, it does not coincide with the distribution of the integrated power spectrum (i.e., roughness of the surface), nor does it obey any of the known extreme statistics limit d...

This paper describes the possibility of estimating the apparent power of a signal component using the interpolation of the products of amplitude discrete Fourier transform (DFT) coefficients. As with energy-based approach for the amplitude square estimation of the onechannel signal, the apparent power in the two-channel case can be estimated with the multiplied amplitude DFT coefficients around...

This article consists of a brief discussion of the energy density over time or frequency that is obtained with the wavelet transform. Also an efficient algorithm is suggested to calculate the continuous transform with the Morlet wavelet. The energy values of the Wavelet transform are compared with the power spectrum of the Fourier transform. Useful definitions for power spectra are given. The f...

The angular power spectra of the infrared maps obtained by the DIRBE (Diffuse InfraRed Background Experiment) instrument on the COBE1 satellite have been obtained by two methods: the Hauser-Peebles method previously applied to the DMR maps, and by Fourier transforming portions of the all-sky maps projected onto a plane. The two methods give consistent results, and the power spectrum of the high...

the ardabil geothermal area is located in the northwest of iran, which hosts several hot springs. it is situated mostly around the sabalan mountain. the sabalan geothermal area is now under investigation for the geothermal electric power generation. it is characterized by its high thermal gradient and high heat flow. in this study, our aim is to determine the fractal parameter and top and botto...