Mahmoud M. Smadi

Study of the reliability of a binary symmetric channel under non-Gaussian disturbances

The field of digital and data communications is becoming increasingly dominant because digital transmission offers data processing options and flexibilities not available with analog transmission. The main feature of a digital communication system is that during a finite interval of time, it sends a waveform from a finite set of possible waveform. One of the most important and fundamental models of communications channels is the binary symmetric channel (BSC). An important measure of system performance in a digital communication system is the probability of error. In this paper, the probability of error, the reliability, the entropy and the channel capacity of a BSC model are studied under non-Gaussian noise disturbances. Namely, Cauchy, Laplace and logistic distributions are considered. It is found that the reliability of the signaling system is low under non-Gaussian noise distributions compared to the Gaussian noise distribution. Several methods were used to reduce the error probability. The amount of improvement in reliability using the reduction methods is higher in the case of Gaussian noise. In order to achieve high reliability under non-Gaussian noise distribution, it is required to increase signal-to-noise ratio (SNR) and increase number of repetitions when sending the same signal different times. Finally, it is observed that increasing the reliability for Cauchy distribution noise has totally failed based on sending the same signal different times and summing the received signals. Copyright

Safety evaluation of p-synephrine following 15 days of oral administration to healthy subjects: A clinical study

Extracts of bitter orange (BOE, Citrus aurantium L.) and its primary protoalkaloid p‐synephrine are extensively consumed as dietary supplements. p‐Synephrine is also present in foods and juices prepared from various Citrus species. The safety of p‐synephrine has been questioned as a result of structural similarities with ephedrine. This study assessed the cardiovascular (stimulant) and hemodynamic effects of BOE (49 mg p‐synephrine) daily given to 16 healthy subjects for 15 days in a placebo‐controlled, cross‐over, double‐blinded study. A physical evaluation by a cardiologist, as well as heart rates, blood pressures, and electrocardiograms were determined, and blood samples were drawn at baseline, and Days 5, 10, and 15. Serum levels for caffeine and p‐synephrine were measured at 1 and 2 weeks. Subjects completed a 10‐item health and metabolic questionnaire at baseline and on Day 15. No significant changes occurred in heart rate, electrocardiograms, systolic blood or diastolic pressures, blood cell counts, or blood chemistries in either the control or p‐synephrine treated groups at any time point. No adverse effects were reported in response to the bitter orange (p‐synephrine). Caffeine consumed by the participants varied markedly. Under these experimental conditions, BOE and p‐synephrine were without stimulant (cardiovascular) and adverse effects.

Phase and magnitude extraction using cepstrum and higher order statistics

Retrieving phase and magnitude information from observed distorted system is an essential problem in many practical applications of digital signal processing. This paper describes a method for extracting signal phase and magnitude information using higher order cumulants and higher order cepstra. Simulation results are presented that demonstrate the performance of this method.

Bayes estimation of binary time series

Abstract This paper will develop Bayesian estimation for first order stationary autoregressive model for binary time series. Posterior distributions and Bayes estimates were derived under conjugate priors based on quick counting of the number of 1 runs. Numerical results by simulation demonstrate the Bayesian estimation.