Estimation of conductive and non-conductive spherical geometrical parameters as a model of unexploded ordnance with electromagnetic induction data using genetic algorithm

Identification and detection of unexploded ordnance is of particular importance due to life and environmental problems, and due to the presence of many fragments left from the explosion of ordnance, their separation is very important. In this article, in order to separate the unexploded ordnance, spherical geometrical parameters are obtained in two conductive and non-conductive states by using electromagnetic induction data. Electromagnetic responses in the frequency domain and in the induction range, in two modes: the eddy current response caused by the stimulation of the conductive body by the magnetic field and the channel current response due to the disturbance created in the radiating electric field in terms of the sphere response, considering a quantity called the coefficient Polarization is considered and the objective function is determined with the obtained equations. To generate the data, the rotation of the coaxial transmitter and receiver coils, as well as the frequency change of the radiation fields, were used simultaneously to obtain the buried anomaly parameters. In this research, genetic algorithm method with Roulette cycle was used to estimate the parameters. In the genetic algorithm, each randomly generated response is called a chromosome, and a set of chromosomes is called a population. Chromosomes are composed of genes and their values are binary numbers. The value of each chromosome is measured by a function called fit, which measures the usefulness and appropriateness of the solution for the given problem. In this work, the induced voltage was obtained by simultaneously sweeping the frequency (between 18 and 20 kHz with 21 samples) and the angle of the turns with the horizon (between 0 and π in 61 samples) and a real response of 1281 points. In the genetic algorithm, the voltages induced in each response (chromosome) are compared with the voltages obtained in the actual response and the fitting function is defined by calculating the inverse of the mean square error. Chromosome has a better response that has a smaller mean squared error (the inverse of a larger mean squared error). With this process, half of the chromosomes are selected and used in the next generation. In the next generation, the selected chromosomes are combined with each other and produce new chromosomes called children. In one generation, a number of chromosomes undergo mutations in their genes, in which each chromosome has up to 3 It will have random mutations in its genes. The chromosome that is maintained in the population for the next generation is selected by Darwin's law of evolution. A chromosome with a higher fitness value has a higher probability of being selected again in the next generation. After several generations, the chromosome value converges to a specific value that is the best solution for the problem. To validate the method, electromagnetic induction data with 5% noise was used. The obtained results show that the used method has an acceptable ability to estimate the parameters.