Performance of the Product of Three Nakagami-m Random Variables

An output signal from a multi-section wireless relay communication system is equal to the product of the signal envelopes from individual sections. In this paper, a three-sections relay system is considered in the presence of Nakagami-m fading at each section. First, random variable (RV) is formed as the product of three Nakagami-m RVs. For such product, the moments are determined in the closed forms. The first moment is the mean of the signal; the second moment is the average power of the signal, and the third moment is skewness. Then, the Amount of Fading (AoF) is calculated. AoF is a measure of the severity effect of fading in a particular channel model. Besides, all system performance are shown graphically and the parameters influence has been analyzed and discussed

Health risk assessment of natural and artificial radionuclides in medicinal plants

In the present work, we determined activity concentrations of ten Medicinal herbs using gamma spectrometry. The radioactivity concentration of 226 Ra, 232 Th, 40 K and 137 Cs were 2.82, 0.63, 984.32, 0.28 Bq/kg, respectively. These doses are not hazardous to the general public's health. The mean values of radium equivalent activity (Raeq), absorbed dose rates (D), annual effective dose (De) and external hazard index (Hex) are 79.51 Bq/kg, 42.73 nGy-1 , 52.40 µSv and 0.21, respectively. Medicinal plants used to make tea do not contain a concentration of tested radionuclides that would cause negative consequences to one's health.Publishe

First and Second Order Characteristics of a Wireless Three-hop Relay Channel with the Presence of Rayleigh Fading, Journal of Telecommunications and Information Technology, 2020, nr 2

In this paper, a wireless three-hop relay communication system operating in a Rayleigh multipath fading environment is analyzed. The output signal from such a system is a product of signal envelopes from all sections, meaning that it is actually a product of three random variables (RVs) with Rayleigh distribution. We considered here the first-order characteristics: probability density function (PDF), cumulative distribution function and outage probability (OP). Then, the moments and amount of fading (AoF) were derived in the closed forms. The second order characteristics we present include the following: level crossing rate (LCR) and average fade duration (AFD). A few graphs are given to show the impact of the specific parameters of the wireless three-hop relay syste

Product of Three Random Variables and its Application in Relay Telecommunication Systems in the Presence of Multipath Fading, Journal of Telecommunications and Information Technology, 2019, nr 1

In this paper, the product of three random variables (RVs) will be considered. Distribution of the product of independent random variables is very important in many applied problems, including wireless relay telecommunication systems. A few of such products of three random variables are observed in this work: the level crossing rate (LCR) of the product of a Nakagami-m random variable, a Rician random variable and a Rayleigh random variable, and of the products of two Rician RVs and one Nakagami-m RV is calculated in closed forms and presented graphically. The LCR formula may be later used for derivation of average fade duration (AFD) of a wireless relay communication radio system with three sections, working in the multipath fading channel. The impact of fading parameters and multipath fading power on the LCR is analyzed based on the graphs presented

Debugging of ORNL series of mathematical phantoms of human body

Series of mathematical phantoms of human body, given by Oak Ridge National Laboratory (ORNL), was programmed as input files for MCNP-4B code. Detailed check of geometry of these phantoms performed by MCNP-4B, discovered some minor errors, that resulted in overlapping of some organs. Three types of errors were found and described here: (a) colon overlaps with pelvis bone; (b) facial skeleton penetrate the head skin, and (c) esophagus overlaps with stomach. These errors prevent correct execution of program. Proposal for correction of these errors are given in this paper

Radon levels and resulting effective doses of residents in Gornja Stubla at Kosovo applying dosimetric lung models based on ICRP 65 and ICRP 66 methodology

The town Gornja Stubla, situated in the South-West part of Kosovo, is a community with high indoor radon level due to its geochemical background. Radon activity concentration in indoor air has been measured by exposing the 960 track-etch detectors for one year, in 172 rooms of 65 dwellings. Annual averages of concentration ranged from 35 Bq/m3 to 6010 Bq/m3. In a first attempt, the effective doses of residents have been calculated applying the ICRP 65 methodology, based on the average radon concentration for the dwelling and for concentrations in the rooms of a dwelling in which they spend fractions of the entire time spent indoors. Both seasonal and annual doses have been calculated. The annual values were in the range of 0.6−107 mSv/a with an average value of 8.6 mSv/a. As nest step we considered that effective dose, being influenced by a number of different parameters and divided into subject and aerosols related parameters, is connected with two crucial parameters, namely, the Dose Conversion Factor (DCF) [mSv/WLM] for a particular person (accounting for real gender, age and physical activity level) and indoor radon concentration and its short lived progeny at field area. Therefore, software based on ICRP Publication 66 was developed for determination of effective dose per unit inhaled activity of radon progeny, DCF. According to the results of indoor radon measurements in the area of Gornja Stubla, the effective dose for its population was estimated by using the dosimetric lung model. The results, obtained according to ICRP 66, were compared with results calculated according to ICRP Publication 65