imperialist competitive algorithm (ica)

Determining the internal structure of objects such as identification of impurities, estimation of mechanical properties and identification of internal boundaries and cavities is one of the important issues in industries. Objective of the present article is to investigate the effect of the mechanical properties and the effect of the location of the interfacial boundary in solving the inverse problem of identifying the internal boundaries of a Non- homogeneous body, consisting of two homogeneous bodies, along with the estimation of the modulus of elasticity and Poisson's ratio of its components. The solution has been done using the combination of the numerical method of boundary elements method along with the optimization method of the Imperialist Competitive Algorithm (ICA) and the simplex method. The obtained results, show the effectiveness of the ICA optimization and the simplex method in estimating the mechanical properties and identifying the interfacial boundary configurations. But, as the boundary approaches the lower part of the material and the mechanical properties approach, the boundary estimation error increases to 8.65% for the solved examples, which again indicate the strength of this method to estimate the boundary. Also, in the investigation of the effect of unavoidable errors in the measurement of displacements, with the increase in the error percentage, the convergence to the real boundary is reduced, so that for error greater than 5%, the geometry of the internal boundaries converges to unrealistic boundaries and the calculations are no longer valid.

One of the applications of optimization methods is solving the inverse problems of identifying internal boundaries, estimating the mechanical properties of materials and etc. In most of the articles, due to the simplicity of the relationships, the cases where the material is a homogeneous body have been considered, But in industry, when two molten material are combined together, there is a possibility that the resulting material is non-homogeneous material.In this article, identifying the geometry of the irregular internal boundaries between three materials and estimating the mechanical properties is presented. The intermediate material has a variable modulus of elasticity. This problem has been studied by combining three methods of colonial competition algorithm, simplex and conjugated gradian method along with the numerical method of Boundary Elements Method. The effect of the type and hardness of the constituent materials of the non-homogeneous body and the effect of the geometry and position of the internal boudaries on the convergence have been investigated. The obtained results indicate the power and ability of the presented method to estimate unknown parameters.

Identification of the thermal conductivity of a functionally graded material (FGM) is considered as an inverse heat conduction problem. ýIn this investigation, the measurements of the temperatures on the portion of the 2D body where heat flux is specified as the boundary ýcondition and/or the heat flux on the portion of the boundary where temperature is specified as the boundary condition are used as ýadditional data needed to identify the thermal conductivity of the FGM domain in an inverse procedure. The thermal conductivity is ýapproximated as a quadratic function of only one direction, and therefore three constant coefficients should be estimated simultaneously.ýþ þThe solution of the direct heat conduction problem forþ þFGM domain is obtained using the boundary elements method (BEM).ýþ þThe ýimperialist competitive algorithm (ICA) which is an evolutionary and meta-heuristic global optimization is used to identify the constants ýin the thermal conductivity function of the quadratic FGM. An inverse computer code is developed which employs the boundary ýtemperature and heat flux measurements data obtained by solving the direct boundary elements code with known thermal conductivity. ýTo show the feasibility and effectiveness of the developed inverse code, a number of example problems are solved and results are ýverified.ý

One of the most important issues in industry, particular casting industry is to determine the internal structure of objects such as identifying the interfacial boundary configurations between material, identification of impurities or mechanical properties of the material. The objective of the present inverse problem is to identified simultaneously two regular interfacial boundary configurations and mechanical properties of the components of a multiple (three) connected domains using a discrete number of displacement measurements obtained from an uniaxial tension test. A unique combination of a global optimization method i.e. the Imperialist Competitive Algorithm (ICA) and local optimization methods i.e. Simplex Method (SM) along with the inverse application of the Boundary Elements Method (BEM) are employed in an inverse software package. A fitness function, which is the summation of squared differences between the measured displacements and computed at identical locations on the exterior boundary, is minimized. The obtained results (run-time and error-rate), clearly demonstrate the efficiency of this present algorithm (the Imperialist Competitive Algorithm and Simplex Method) to optimize the objective function and the estimation simultaneously two regular interfacial boundary configurations and mechanical properties.

The design of the structural supports has always been practically important in engineering applications. In addition to holding a structure properly، supports can also be utilized to improve the structural performances. In this study، by using modified finite element method (MFEM) and Imperialist Competitive Algorithm (ICA)، the maximum of bending moment was minimized. In this paper both elastic and rigid supports are taken into account. As compared to other design optimization methods، ICA is robust، more efficient، and requiring fewer number of function evaluations، while leading to better quality of results. Appling the modified finite element method not only reduces computational cost and increases convergence rate، but also reach the global optimum position of supports. Three classical examples are given to demonstrate the validity and capability of the proposed optimization procedure for finding the global support positions. Results show that support position optimization by using present method، can reduce the maximal moment significantly، and deserves more investigation.