Pattern Synthesis in Time-Modulated Arrays Using Heuristic Approach

Time-modulation principle evolves as an emerging technology for easy realization of the desired array patterns with the help of an additional degree of freedom, namely, “time.” To the antenna community, the topic, time-modulated antenna array (TMAA) or 4D antenna arrays, has got much attention during the last two decades. However, population-based, stochastic, heuristic evolutionary algorithm plays as an important protagonist to meet the essential requirements on synthesizing the desired array patterns. This chapter is basically devoted to understand the theory of different time-modulation principles and the application of optimization techniques in solving different antenna array synthesis problems. As a first step, the theory of time-modulation principles and the behaviors of the sideband radiation (SBR) that appeared due to time modulation have been studied. Then, different important aspects associated with TMAA synthesis problems have been discussed. These include conflicting parameters, the need of evolutionary algorithms, multiple objectives and their optimization, cost function formation, and selection of weighting factors. After that, a novel approach to design a time modulator for synthesizing TMAAs is presented. Finally, discussing the working principle of an efficient heuristic approach, namely, artificial bee colony (ABC) algorithm, the effectiveness of the time modulator and potentiality of the algorithm are presented through representative numerical examples

An Empirical Modeling and Evaluation Approach for the Safe use of Industrial Electric Detonators in the Hazards of Radio Frequency Radiation

27-33The major causes of radio frequency radiation hazards are the transmitting antennas of radio, TV, radar, cell phones, wireless data acquisition systems and global positioning systems in the new age of communication technology using various modulation schemes such as amplitude modulation (AM), frequency modulation (FM) etc. The transmitting antennas of these communication devices generate electromagnetic fields (EMFs). Under such conditions, electric detonator wires work as receiving antenna and pickup sufficient energy from electromagnetic fields to initiate an accidental explosion. There have been several instances of accidental firing of detonators by radio frequency pickup. In this study an attempt has been made to minimize such explosions and to provide a basis for the assessment and simulation of the radio frequency radiation hazard parameters associated with industrial electric detonators. This research examines the radiated powers of various frequency bands to determine the safe distance from transmitting antenna. Two empirical relationships for the estimation of minimum safe distance (MSD) have been suggested based on mathematical simulation. Using these relations desired MSDs have been calculated for the relevant frequency bands. The values obtained have been compared with the experimental values available that demonstrated strong agreement between them. The average percentage deviations of calculated MSDs from suggested relations are found between 0.096% and 10.718%, with regression coefficient 0.970 ≤ R ≤ 1. This reflects the soundness of the proposed empirical relations. The blasting engineers, detonator designers and researchers may use these relations as a handy tool to prevent undesired explosions by maintaining minimum safe distance in radio frequency prone hazardous areas

Refractive index of different perovskite materials

The perovskite solar cell technologies are the hope of satisfying the huge demand of tomorrow’s energy requirements. The inorganic, organic and mixed perovskite materials are the backbone of modern solar cells. The energy band gap and refractive index of perovskites help in selecting proper materials for solar cell, solid-state lighting and lasing applications. In this paper, various perovskite materials and different energy band gap–refractive index relations have been studied. A simple empirical relationship between energy gap ‘Eg’ and refractive index ‘n’ for perovskites has been developed and proposed. Using this relationship, refractive indices of 33 different perovskites have been calculated and compared with their reported values. Also, the refractive indexes of about 140 new perovskites have been predicted and reported probably for the first time. The researchers interested in refractive index calculation may use the proposed relation and need not to worry for complex experimental setup

An Empirical Modeling and Evaluation Approach for the Safe use of Industrial Electric Detonators in the Hazards of Radio Frequency Radiation

The major causes of radio frequency radiation hazards are the transmitting antennas of radio, TV, radar, cell phones, wireless data acquisition systems and global positioning systems in the new age of communication technology using various modulation schemes such as amplitude modulation (AM), frequency modulation (FM) etc. The transmitting antennas of these communication devices generate electromagnetic fields (EMFs). Under such conditions, electric detonator wires work as receiving antenna and pickup sufficient energy from electromagnetic fields to initiate an accidental explosion. There have been several instances of accidental firing of detonators by radio frequency pickup. In this study an attempt has been made to minimize such explosions and to provide a basis for the assessment and simulation of the radio frequency radiation hazard parameters associated with industrial electric detonators. This research examines the radiated powers of various frequency bands to determine the safe distance from transmitting antenna. Two empirical relationships for the estimation of minimum safe distance (MSD) have been suggested based on mathematical simulation. Using these relations desired MSDs have been calculated for the relevant frequency bands. The values obtained have been compared with the experimental values available that demonstrated strong agreement between them. The average percentage deviations of calculated MSDs from suggested relations are found between 0.096% and 10.718%, with regression coefficient 0.970 ≤ R ≤ 1. This reflects the soundness of the proposed empirical relations. The blasting engineers, detonator designers and researchers may use these relations as a handy tool to prevent undesired explosions by maintaining minimum safe distance in radio frequency prone hazardous are