An optimization method based on the microgenetic algorithm(MGA) is presented for the design of multilayered radar absorbing materials made of tetrapod-shaped ZnO *** optimization procedure is designed for a given thic...
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An optimization method based on the microgenetic algorithm(MGA) is presented for the design of multilayered radar absorbing materials made of tetrapod-shaped ZnO *** optimization procedure is designed for a given thickness and the optimization conditions,which are different in order to meet the practical requirements in the different frequency bands(the range of 2～18GHz).The effects of the thickness,the number of layers,and the restrained conditions on the optimization results are discussed in detail.
In this study, we investigate a method to detect damage in a laminated composite structure by analyzing its dynamic response to impact loads. The combined finite element method (FEM) with seven degrees of freedom (DOF...
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In this study, we investigate a method to detect damage in a laminated composite structure by analyzing its dynamic response to impact loads. The combined finite element method (FEM) with seven degrees of freedom (DOF) and the advanced microgenetic algorithm described in this paper may allow us not only to detect the damaged elements but also to find their locations and the extent of damage. A high order shear deformation theory (HSDT) is used to predict the structural behavior and to detect damage of laminated composite plates. The effects of noise associated with the uncertainty of measurements due to the complex nature of composites are considered for [0/90](s) and [+/- 45](s) layup sequences. The results indicate that the new method is computationally efficient in characterizing damage for complex structures such as laminated composites.
An optimization technique based on the microgenetic algorithm (MGA) is presented for the design of multilayered radar absorbing materials made of tetrapod-shaped ZnO whisker in this paper. The fast optimization proced...
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ISBN:
(纸本)078039433X
An optimization technique based on the microgenetic algorithm (MGA) is presented for the design of multilayered radar absorbing materials made of tetrapod-shaped ZnO whisker in this paper. The fast optimization procedure is designed for a given maximum thickness and the optimization conditions are different in order to meet the practical requirements in the different frequency bands (the range of 2 similar to 18GHz). The effects of the thickness, the number of layers, and the restrained conditions on the optimization results are discussed in detail.
An efficient and powerful full-wave electromagnetic technique is presented to characterise and design periodic metamaterial structures. First, the spectral finite-difference time-domain (FDTD) method with periodic bou...
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An efficient and powerful full-wave electromagnetic technique is presented to characterise and design periodic metamaterial structures. First, the spectral finite-difference time-domain (FDTD) method with periodic boundary conditions and uniaxial perfect matched layer is employed to predict the performance of a mushroom-like artificial magnetic conductor (AMC) surface and further extended to characterise a negative-refractive-index material consisting of lumped and distributed transmission-line elements. Then, a new computational technique is developed to design and optimise periodic metamaterial structures by integrating the spectral FDTD method with a genetic algorithm (GA), namely the micro-genetic algorithm. This computational technique is successfully applied to design and optimise single-band and dual-band AMC structures consisting of a frequency-selective surface and a ground plane. It is demonstrated that the GA/FDTD technique is a very effective approach for the design and optimisation of periodic metarnaterial structures consisting of dielectrics and conductors of arbitrary configurations.
Engine mount rubber (EMR) is an important vehicle component to isolate the vehicle structure from engine vibration. The paper deals with optimal design of EMR considering the material stiffness and fatigue strength of...
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Engine mount rubber (EMR) is an important vehicle component to isolate the vehicle structure from engine vibration. The paper deals with optimal design of EMR considering the material stiffness and fatigue strength of a rubber. The objective is to minimize both the weight and the maximum stress of EMR, and to maximize the fatigue life cycle subjected to constraints on the static stiffness of the rubber. A hyperelastic rubber model with a high strain range is used to accommodate the non-linear behaviour of EMR in the stress and fatigue analysis. In the context of approximate optimization, a back-propagation neural network is used to construct global response surfaces between input design variables and output responses of objective functions and constraints. A microgenetic algorithm (MGA) is adopted as a global optimizer in order to consider the inherent non-linearity of analysis model as well. A multiobjective optimization result shows improved design performances regarding the reduction in the maximum stress and the increase in the life cycle with acceptable material stiffness.
The main focus of this paper is on the application of Genetic algorithm (GA) to search for an optimal solution to a reatisticafly formulated economic dispatch (ED) problem. GA is a global search technique based on pri...
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ISBN:
(纸本)078039156X
The main focus of this paper is on the application of Genetic algorithm (GA) to search for an optimal solution to a reatisticafly formulated economic dispatch (ED) problem. GA is a global search technique based on principles inspired from the genetic and evolution mechanism observed in natural biological systems. A major drawback of the conventional GA (CGA) approach is that it can be time consuming. The micro-GA (mu GA) approach has been proposed as a better time efficient alternative for some engineering problems. The effectiveness of CGA and mu GA to solving ED problem is initially verified on an IEEE 3-generating unit, 6-bus test system. Simulation results obtained on this network using CGA and mu GA validate their effectiveness when compared with the published results obtained via the classical and the Hopfield neural network approaches. Finally, both GA approaches have been successfully applied to the coordination of the Nigerian 31-bus system fed by four thermal and three hydro generating units. Herein, use has been made of the loss formula developed for the Nigerian system from several power flow studies. For the Nigerian case study, the mu GA is shown to exhibit superior performance than the CGA from both optimal generation allocations and computational time viewpoints.
In this paper, we present a procedure for synthesizing broad-band microwave absorbers incorporating frequency-selective surface (FSS) screens embedded in dielectric media using a binary coded genetic algorithm (GA) [1...
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In this paper, we present a procedure for synthesizing broad-band microwave absorbers incorporating frequency-selective surface (FSS) screens embedded in dielectric media using a binary coded genetic algorithm (GA) [1], [2].The GA simultaneously and optimally chooses the material in each layer, thickness of each layer, FSS screen periodicity in the x- and y-directions, its placement within the dielectric composite, and the FSS screen material, Additionally, the GA generates the cell structure of the FSS screen. The result is a multilayer composite that provides maximum absorption of both TE and TM waves for a prescribed range of frequencies and incident angles. This technique automatically places an upper bound on the total thickness of the composite.
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