Genetic Optimization Of Multi-layer Nano-absorbing Materials, Design And Numerical Calculation

With the development of technology,absorbing materials have been applied in stealth widelier and widelier.The stealth of weapons and equipment can significantly improve military efficiency. Simultaneously,absorbing materials have been widely applied in many civil areas such as the safe protection for human body,microwave darkrooms, the security of information, electromagnetic compatibility,and so on.The traditional absorbing materials are usually heavy and thick with narrow absorbing broadband,they can't satisfy the requests of weaponry stealth in the modern battlefield. Consequently,there is an urgent need to develop a new generation of absorbing materials with high performances of light-weight,thin-structure,broad-band and strong-absorption. In recent years,there have been some new types of absorbing materials such as nanometer absorbing materials,hand property absorbing materials,crystal iron fiber absorbing materials,plasma absorbing materials ,intelligent absorbing materials,and so on.Among them,Nanometer absorbing materials because of its own special absorbing mechanism,coupled with the advantages of light and thin,have been the study hotspot of the new generation absorbing materials,developing toward the directions of multilayer,complex and coating.While designing the materials with more layers,the relatively simple design means in the laboratory appear helpless for nanometer absorbing materials,consequently,we need the help of computer aided design for optimization.For synthesis,there are many choices of old optimization algorithms, including conjugate gradient methods, quasi-Newton methods,the simplex method and the simulated annealing (SA) method.However, they all have some drawbacks. For instance, the convergence process often depends on gradient information, influenced greatly by initial solution,and may induce local optimization,which will reduce the efficiency of computer design. In comparison with above traditional techniques,genetic algorithms (GA's) proposed by proffessor Holland from America,as one representative of a host of new global optimization techniques, have become very popular for the solution of electromagnetic design problems.GA's have the following features: robustness, capacity to search without gradient information,independence of the initial guess, and ability to operate on discrete and continuous parameters simultaneously.They are suitable for handling with such problems as multi-parameter optimization of complex systems design for multilayer absorbing materials,consequently,have been widely applied in the optimal designs of microwave absorbing materials and gained sustainable development in recent years.For the sake of new generation absorbing materials with light-weiht,thin-structure,broad-bandwidth and strong-absorption,this paper puts forward the corresponding objective functions used to evaluate the performances of design results.Based on the electromagnetic parameters of actual nanometer absorbing materials from database,first of all,we have adopted standard genetic algorithm with constraints for single objective to design high performance absorbing coatings,discussing the corresponding design results.Because of the disadvantage of local optimization(also called prematurity),we put forward adaptive genetic algorithm(AGA) to improve on the programmes,getting the satisfactory results.In addition,we also introduce multi-objective genetic algorithm to the design of multilayer absorbing materials,further expangding the fields of computer aided design for absorbing materials.Using the new Non-dominated Sorting Genetic Algorithm II (NSGA-II),we have discussed the design programmes for two objectives and three objectives respectively,finally getting the new generation absorbing coatings with the characteristics of light-weiht,thin-srtucture,broad-bandwidth and strong-absorption,which have important value for practical works.