Abstract The frequency-dependent amplitude-versus-offset (FAVO) method has become a practical for fluid detection in sand reservoirs. At present, most FAVO inversions are based on the assumption that reservoirs isotropy, but application effect is not satisfactory fractured Hence, we analyse frequency variation characteristics of anisotropy parameters tight sandstone new petrophysical model, and...

This paper deal with the symbol timing issue of an OFDM system in fast varying channel. Symbol timing offset (STO) estimation is a major task in OFDM. Most of existing methods for estimating STO used cyclic prefix or training sequences. In this paper, we consider a new system for STO estimation using constant amplitude zero auto-correlation (CAZAC) sequences as pilot sequences in conjunction wi...

Common-midpoint (CMP) stacking technique plays an important role in enhancing the signal-to-noise ratio (SNR) in seismic data processing and imaging. Weighted stacking is often used to improve the performance of conventional equalweight stacking in further attenuating random noise and handling the amplitude variations in real seismic data. In this study, we propose to use a hybrid framework of ...

The use of multi-level (QAM-type) modulations in mobile communications affected by fading and Doppler shift imposes a tight control on the carrier frequency offset if quasi-coherent detection is a goal. This aspect is taken into account by the receiver herein proposed. A 16-DAPSK (differential amplitude phase shift-keying) scheme is considered, with one bit being absolutely encoded in amplitude...

This paper is devoted to the design of a sliding-mode control scheme for a buck-based inverter, with programmable amplitude, frequency, and dc offset, with no external sinusoidal reference required. A general procedure for obtaining an autonomous (time independent) switching surface from a time-dependent one is presented. For this surface, the system exhibits a zeroth-order dynamics in sliding ...

A new method for analyzing symmetry and normalcy of gait patterns is explained. This method utilizes eigenvectors to compare waveforms. The right and left limbs of a single subject are compared to determine symmetry. To determine normalcy, a single limb from a subject is compared to a normative file created from the average of healthy control subjects. The analysis method provides four measures...

The conventional Markov chain Monte Carlo (MCMC) method is limited to the selected shape and size of proposal distribution and is not easy to start when the initial proposal distribution is far away from the target distribution. To overcome these drawbacks of the conventional MCMC method, two useful improvements in MCMC method, adaptive Metropolis (AM) algorithm and delayed rejection (DR) algor...

In the laboratory, thresholds for stereoscopic depth perception are usually determined by asking observers to discriminate between a stimulus with a given depth offset and its mirror image. Threshold is most often defined as the disparity difference that yields 75% or 83% correct responses. Disparities used for clinical tests of stereopsis are much higher. Here it is argued that, among other fa...

A fully differential programmable gain amplifier (PGA) with constant transfer characteristic and very low power consumption is proposed and implemented in a 130 nm CMOS technology. The PGA features a gain range of 4 dB to 55 dB with a step size of 6 dB and a constant bandwidth of 10–550 kHz. It employs two stages of variable amplification with an intermediate 2nd order low-pass channel filter. ...