Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/153967
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dc.titleDESIGN OF FREQUENCY SELECTIVE SURFACES USING A GENETIC ALGORITHM-DRIVEN FINITE-DIFFERENCE TIME-DOMAIN METHOD
dc.contributor.authorKHOO WEI MING
dc.date.accessioned2019-05-10T04:54:42Z
dc.date.available2019-05-10T04:54:42Z
dc.date.issued2003
dc.identifier.citationKHOO WEI MING (2003). DESIGN OF FREQUENCY SELECTIVE SURFACES USING A GENETIC ALGORITHM-DRIVEN FINITE-DIFFERENCE TIME-DOMAIN METHOD. ScholarBank@NUS Repository.
dc.identifier.urihttps://scholarbank.nus.edu.sg/handle/10635/153967
dc.description.abstractThe design of Frequency Selective Surfaces (FSS) to meet a desired frequency response is an arduous task due to the complex nature of the variables involved. The Genetic Algorithm (GA) is thus a useful technique to solve the optimisation problem as it can handle complex combinatorial variables. Moreover, the GA has a wide range of adjustable parameters which make it a robust method for optimisation. Of the various crossover and mutation schemes tested, GA performed the best with a high degree of elitism, uniform crossover with mutation (probability of mutation 0.01) and single child from a single parent pair. The GA was able to find solutions that fitted the transmission and reflection coefficients of 2 test target FSS screens with a high level of accuracy, even though visually the designs looked starkly different. Both solutions were within 5.00 % of the global optimum. This verified the results from the experiments done without the PB-FDTD code. The number of function evaluations needed were 3,907 and 3,844, and each function evaluation took approximately 8 minutes on a Pentium 3 933 MHz 128 Mb RAM machine. Initial work has already been started on including other design parameters such as relative permitivities of the dielectric layers, thickness, and position of the FSS screen, apart from the FSS unit cell metallization. A major obstacle, however, is the timeframe needed for the GA to obtain a solution within a 5.00 % margin. Proposed solutions are porting the presently Windows-based PB-FDTD code into Linux, making use of Linux-based multi-processor parallel computers, or modifying the presently general PB-FDTD code to take further advantage of the problem's geometry. Other numerical methods, such as the method of moments, may be a better option because the FSS composites considered in this problem are generally thin and infinite in the x- and y- directions. The PB-FDTD method though versatile enough to handle a wide range of geometries, is too computationally expensive to use in this context.
dc.sourceSMA BATCHLOAD 20190422
dc.subjectFrequency Selective Surfaces
dc.subjectGenetic Algorithm
dc.subjectPeriodic Boundary
dc.subjectFinite-Difference Time Domain Technique
dc.subjectOptimisation
dc.typeThesis
dc.contributor.departmentSINGAPORE-MIT ALLIANCE
dc.contributor.supervisorANG TENG WAH
dc.contributor.supervisorCHIO TAN HUAT
dc.contributor.supervisorTAPABRATA RAY
dc.description.degreeMaster's
dc.description.degreeconferredMASTER OF SCIENCE IN HIGH PERFORMANCE COMPUTATION FOR ENGINEERED SYSTEMS
dc.description.otherDissertation Supervisors 1. Mr Ang Teng Wah, DSO National Laboratories 2. Dr Chio Tan Huat, DSO National Laboratories 3. Dr Tapabrata Ray, Temasek Laboratories 4. Assoc. Prof. Li Le-Wei, SMA Fellow, NUS
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