sequential quadratic programming

This paper aims to show the capability of hybrid optimization algorithms in finding the proper optimal plan for optimizing complex systems. So design optimization of an unmanned aerial vehicle has been presented as a complicated system by using multidisciplinary design optimization, genetic algorithm, and hybrid optimization algorithm. This study uses a hybrid optimization algorithm from a genetic algorithm as a global optimizer and from sequential quadratic programming as a local optimizer. The optimization problem of this study is a multi-objective design optimization problem in which the considered objective functions are the minimization of takeoff weight and cruise drag force. The considered constraints are related to the deflection of the control surface, stability, and handling quality specifications (damping coefficients, natural frequencies, and time constants). The proposed design optimization problem has been solved by using a hybrid optimization algorithm and genetic algorithm separately, and their results have been compared to each other. Although both optimal designs are acceptable, results show that the optimal design of the hybrid optimization algorithm is better than the optimal design of the genetic algorithm from an objective functions point of view. This issue shows the good performance of a hybrid optimization algorithm for design optimization of complex systems.

In this study, an innovative method for crack identification in buckled plates using differential quadrature element method (DQEM) and sequential quadratic programming (SQP) method is proposed. This study consists of two steps. In first step, a numerical method is applied to calculate the frequencies of buckled cracked plates. Cracks are assumed to be open and modeled as linear rotational spring. Governing equations are extracted considering effects of shear deformations and initial geometric imperfection. Then, considering the solution as summation of static solution (postbuckling) and dynamic solution, the governing equations are converted into two different equation sets; postbuckling equations and vibration equations. The natural frequencies can be obtained solving these equation sets. In second step, SQP optimization method and the method used in first step combined to make a new method for identification of crack specification using natural frequencies. In this step, a weighted sum of square of differences between calculated frequencies and experimental frequencies considered as cost function and used to identify crack properties. Finally, the accuracy and precision of proposed method verified using some experimental and numerical case studies.