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Abd-Alhameed, R. A., Excell, P. S., & Mangoud, M. A. (2005)'Computation of specific absorption rate in the human body due to base-station antennas using a hybrid formulation'. IEEE Transactions on Electromagnetic Compatibility, 47(2), 374-381.Computation of specific absorption rate in the human body due to basestation antennas using a hybrid formulation AbstractA procedure for computational dosimetry to verify safety standards compliance of mobile communications base stations is presented. Compared with the traditional power density method, a procedure based on more rigorous physics was devised, requiring computation or measurement of the specific absorption rate (SAR) within the biological tissue of a person at an arbitrary distance. This uses a hybrid methd of moments/finite difference time domain(MoM/FDTD) numerical method in order to determine the field or SAR distribution in complex penetrable media, without the computational penalties that would result from a wholly FDTD simulation. It is shown that the transmitted power allowed by the more precise SAR method is, in many cases, between two and five times greater than that allowed by standards implementing the power flux density method. KeywordsHybrid method, specific absorption rate (SAR), safety standards, computational dosimetry Disciplines Computer Engineering | Computer SciencesComments ©2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. This paper was published in IEEE Abstract-A procedure for computational dosimetry to verify safety standards compliance of mobile communications base stations is presented. Compared with the traditional power density method, a procedure based on more rigorous physics was devised, requiring computation or measurement of the specific absorption rate (SAR) within the biological tissue of a person at an arbitrary distance. This uses a hybrid methd of moments/finite difference time domain (MoM/FDTD) numerical method in order to determine the field or SAR distribution in complex penetrable media, without the computational penalties that would result from a wholly FDTD simulation. It is shown that the transmitted power allowed by the more precise SAR method is, in many cases, between two and five times greater than that allowed by standards implementing the power flux density method.Index Terms-Hybrid method, specific absorption rate (SAR).

This study introduces a new design method for reconfigurable phased arrays using hybrid differential evolution (DE) and enhanced particle swarm optimisation (EPSO) technique. The proposed technique combines DE and enhanced version of standard PSO with improved mechanism that updates velocities and global best solution. In the hybrid algorithm, DE and EPSO are executed in parallel with frequent information sharing to enhance the newly generated population. To demonstrate the effectiveness of the proposed algorithm over each separate algorithm, examples for designing reconfigurable linear and circular antenna arrays with prescribed null directions are presented. Null steering is achieved by position perturbation of array elements in arbitrary directions with minimum sidelobe level change constraint. Another objective is to minimise the number of mobilised elements by introducing elements selection criteria. Simulation results show that the global search ability of the proposed algorithm is improved when compared with DE and EPSO separately.

One of the main challenges in cognitive radio networks is the ability of secondary users to detect the primary user presence with high probability of detection. In previous research, optimizing cooperative sensing in cognitive radio networks is performed for either a targeted probability of detection or a false alarm. After setting one of the probabilities as an optimization constraint, the other is optimized. In this paper, a guaranteed constant throughput at the secondary users is introduced as a target while optimizing probability of detection for cooperative sensing. Both sensing time values and number of cooperated cognitive radio secondary users are investigated to maximize the probability of detection of primary user. AND and OR hard decision schemes are considered and compared with soft decision scheme which is weighted modified deflection coefficient scheme (W-MDC). It is illustrated that cooperation of all users and utilizing full frames for sensing time will not provide maximum probability of detection. A tradeoff between performances of cognitive radio networks with and without optimization is presented. The effects of varying network sizes, normalized target throughput, maximum frame duration times, and received signal-to-noise ratio at the fusion center are investigated for different fusion rules.

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