Inversion of Oblique Ionograms Based on Hybrid Genetic Algorithm

Abstract

The oblique sounding is a powerful tool for acquiring ionospheric information, and we can get the structural parameters related to ionosphere by inversing the oblique ionogram. Genetic algorithm (GA) is a widely used inversion method which can reduce the non-uniqueness of the inversion problems without depending on the initial estimation, but the accuracy and reliability of GA's inversion results may be decreased due to "premature convergence" and inferior local search ability. So an improved hybrid genetic algorithm (HGA) based on simulated annealing algorithm (SA) is proposed and firstly applied to inversion of oblique ionogram. HGA combines the advantages of GA and SA together and makes full use of them, so it has a strong global search ability and local search ability. To verify the reliability and stability of HGA's inversion results, we firstly use GA, SA, and HGA to inversion of the synthetic oblique ionogram and compare the inversion results of the three algorithms, find that HGA's results are nearest to the real values and its needed iterations are also much smaller than others. The inversion results include the critical frequency, the height of maximum electron density and half-thickness. Then, comparing the influences on inversion results by changing the population size and the total iterations, we find that the HGA effectively reduces the influences. Lastly, we use the three algorithms to invert the real ionograms and compare the inversion results with the vertical data in the midpoint of transmitting and receiving site. The results show that the stability and the searching optimal solution ability of HGA are obviously better than the GA and SA, and its inversion results are reliable, so HGA has strong referential significance and practical value for the inversion of real ionograms.

A Novel Ionospheric Sounding Network Based on Complete Complementary Code and Its Application

“…HGA is an improved genetic algorithm (GA) based on simulated annealing algorithm (SA). It was firstly applied to the inversion of oblique ionogram by Song Huan et al [19]. Because of the combination of the advantages of the two algorithms, HGA has high accuracy and efficiency [20].…”

“…When it is used in oblique inversion, the results of Song Huan’s experiments show that HGA performs better in accuracy and stability than GA and SA. The specific inversion process and the comparison between the parameters (especially the comparison of the foF2 parameters) obtained by using this algorithm on the oblique inversion and the vertical sounding results at the reflection point can refer to [19].…”

“…When the spare date set is abundant, KG has good robustness [24]. (Although different models are used in vertical and oblique inversion, which may cause some inconsistencies between the electron density profiles, but as described in the article [19], the inversion results of foF2 parameters are quite reliable. Referring to the vertical sounding results of the reflection point, 84.62% of the oblique inversion results are within the error of 0.4 MHz).…”

Research progress of CRISPR-Cas9 gene editing technology in construction of cancer models

“…This novel method using CRISPR-Cas9 to generate mouse models of gene fusion will be instrumental for the advancement of cancer research, allowing for the study of treatment response and resistance mechanisms. This study would not have been possible to conduct using knockin mice by traditional embryonic stem (ES) technology, as opposed to the CRISPR-Cas 9 method, the ES system is more time-consuming and economically inefficient [23]. Most notably, in ES models, researchers generate a specific germline mutation or modulate a specific allele in order to produce tissue-specific mutations, resulting in the entire organ carrying the same mutation.…”

An Improved Method for the Inversion of Backscatter Ionograms by Using Neighborhood-Aided and Multistep Fitting

“…However, without prior knowledge, it is difficult to find natural reference sources or arrange artificial cooperative reference sources near the target of interest. Song proposed applying the hybrid GA based on the SAA to the parameter inversion of the ionization map to obtain the complementary advantages of the GA and SAA [12,13]. Experiments have shown that the hybrid algorithm is superior to the GA and SAA in terms of the optimization and stability of inversion.…”