On the Apparent Non-Uniqueness of the Electromagnetic Field Components of Return Strokes Revisited

Recent research work shows that there are four procedures that can be used to calculate the electromagnetic fields from a current source. These different procedures, even though producing the same total field, give rise to field components that differ from one procedure to another. This has led to the understanding that the various field terms that constitute the total field cannot be uniquely determined. In this paper, it is shown that all four field expressions can be reduced to a single field expression, and the various field terms arising from acceleration, uniformly moving, and stationary charges can be uniquely determined. The differences in the field terms arising from different techniques are caused by the different ways of summing up the contribution to the total electric field coming from the accelerating, moving, and stationary charges.

Piezoelectric relaxation of two-dimentional electron gas in InGaN/GaN heterostructures with quantum wells

The article is devoted to the study of the mechanism of piezoelectric scattering of charge carriers in an InGaN/AlGaN/ GaN heterostructures with one filled quantum-confinement subband. The aim of the article is to create a mathematical model that can be used to estimate the kinetic parameters of a two-dimensional electron gas (2DEG) in the structure under study. The results of the calculation of the matrix scattering potentials demonstrated the reliability and consistency on the used model of industrial LED heterostructures with InGaN/GaN quantum wells. It is shown that mechanical stresses in the InGaN/GaN layers lead to an uneven distribution of the total electric field along the active layer. It has been established that the lifetime limiting the mobility of a two-dimensional electron gas in piezoelectric scattering is of the order of 10–9 s.

Piezoelectric relaxation of a two-dimensional electron gas in heterostructures with InGaN/GaN quantum wells

The article is devoted to the study of the mechanism of piezoelectric scattering of charge carriers in an InGaN/AlGaN/ GaN heterostructures with one filled quantum-confinement subband. The aim of the article is to create a mathematical model that can be used to estimate the kinetic parameters of a two-dimensional electron gas (2DEG) in the structure under study. The results of the calculation of the matrix scattering potentials demonstrated the reliability and consistency on the used model of industrial LED heterostructures with InGaN/GaN quantum wells. It is shown that mechanical stresses in the InGaN/GaN layers lead to an uneven distribution of the total electric field along the active layer. It has been established that the lifetime limiting the mobility of a two-dimensional electron gas in piezoelectric scattering is of the order of 10-9 s.

Assessing The Risk Associated with Simultaneous Exposure To Mobile Communication Signals Within 900–2500 MHz in Nigeria

In this study, the total exposure due to signals within GSM 900, GSM 1800, CDMA-1900 and 3G-2100 frequency bands at 200 m from the foot of 120, 100 and 80 base station masts in the Nigerian cities of Lagos, Ibadan and Abuja, respectively, was assessed. A calibrated hand-held spectrum analyser was used to measure the level of power (in dBm) of each signal within the mobile frequency bands. The exposure quotient associated with the combine electric field strengths from the various frequency bands in each city was estimated. The maximum value of total electric field strength at each point in Lagos, Ibadan and Abuja was 0.83 V/m, 0.53 V/m and 1.63 V/m, respectively. This study shows that the exposure quotient due to the simultaneous exposure to the four bands of mobile communication signals in each city is far less than one, as recommend by International Commission on Non-Ionizing Radiation Protection.