The peak-to-average-power ratio (PAPR) is one of the major problems of Orthogonal Frequency Division Multiplexing (OFDM) systems. Various PAPR reduction techniques have been given in the past. Among these techniques, the clipping technique has been widely adopted as a practical scheme because of its low computational complexity and simplicity in implementation, while the pre-coding technique is...

We investigate the detectability of breast cone beam computed tomography images using human and model observers and the variations of exponent, β, of the inverse power-law spectrum for various reconstruction filters and interpolation methods in the Feldkamp-Davis-Kress (FDK) reconstruction. Using computer simulation, a breast volume with a 50% volume glandular fraction and a 2mm diameter lesion...

Recently, the fixed-pole design of parallel second-order filters has been proposed to accomplish arbitrary frequency resolution similarly to Kautz filters, at 2/3 of their computational cost. This paper relates the parallel filter to the complex smoothing of transfer functions. Complex smoothing is a well-established method for limiting the frequency resolution of audio transfer functions for a...

Medical image registration methods which use mutual information as similarity measure have been improved in recent decades. Mutual Information is a basic concept of Information theory which indicates the dependency of two random variables (or two images). In order to evaluate the mutual information of two images their joint probability distribution is required. Several interpolation methods, su...

For 30 male and 30 female talkers, distributions of short-term rms speech levels, relative to the corresponding long-term rms levels, were determined in each of eight 1/3-oct bands for six short-term measurement intervals. Consecutive, Hanning-windowed, 20-ms time records were combined to produce nominal measurement intervals ranging from 20 to 120 ms. For each measurement interval, mean distri...

The theory of cyclostationarity has emerged as a new approach to characterizing a certain type of nonstationary signals. Many aspects of the spectral analysis of cyclostationary signals have been investigated but were essentially based on the use of the smoothed cyclic periodogram. This paper proposes a cyclic spectral estimator based on the averaged cyclic periodogram which benefits from bette...

The normal modes spectra of the Earth’s free oscillations contain valuable information on the longest wavelength three dimensional structure of the Earth’s interior. Dahlen (1982) first showed that the optimum record length for measuring eigenfrequencies and decay rates of normal modes using a Hanning taper is 1.1 Q cycles. Since typical modal Q values lie in the range 10 of to 10, optimum wind...

The smooth predictable envelope and quasi-periodicity of impulse response allows for potential ways to design ultralow-complexity FIR filters. By introducing an extrapolated impulse response technique, a first attempt successfully reduced the arithmetic complexity of FIR filter from oðNÞ to oð ffiffiffiffiffiffiffi 2N p Þ comparing with direct form. However, this conventional way may suffer fro...

Introduction:  The  purpose  of  this  study  is  to  define  the  optimal  parameters  for  the  tomographic  reconstruction procedure in a routine single photon emission tomography. The Hoffman brain phantom  is modified to evaluate the reconstruction method. The phantom was imaged in a 3 and 2-dimensional  conformation and the results were compared.   Materials  and  Methods:  The  2D  phant...

Introduction: Filtering can greatly affect the quality of clinical images. Determining the best filter and the proper degree of smoothing can help to ensure the most accurate diagnosis. Methods: Forty five patient’s data aquired during brain phantom SPECT studies were reconstructed using filtered back-projection technique. The ramp, Shepp-Logan, Cosine, Hamming, Hanning, Butterworth, Metz...