Iranian Journal of Numerical Analysis and OptimizationIranian Journal of Numerical Analysis and Optimization
http://iranjournals.nlai.ir/2547/
Sun, 29 Mar 2020 17:22:36 +0100FeedCreatorIranian Journal of Numerical Analysis and Optimization
http://iranjournals.nlai.ir/2547/
Feed provided by Iranian Journal of Numerical Analysis and Optimization. Click to visit.An extension of the quasi-Newton method for minimizing locally Lipschitz functions
http://iranjournals.nlai.ir/2547/article_610346_83181.html
We present a method to minimize locally Lipschitz functions. At first, a local quadratic model is developed to approximate a locally Lipschitz function. This model is constructed by using the ϵ-subdifferential. We minimize this local model and compute a search direction. It is shown that this direction is descent. We generalize the Wolfe conditions for finding an adequate step length along this direction. Next, the method is equipped with a quasi Newton approach to update the local model and its globally convergence is proposed. Finally, the proposed algorithm is implemented in MATLAB environment on some standard nonsmooth optimization test problems and compared with some algorithms in the literature.Fri, 04 Oct 2019 20:30:00 +0100Chebyshev pseudo-spectral method for optimal control problem of Burgers’ equation
http://iranjournals.nlai.ir/2547/article_610347_83181.html
In this study, an indirect method is proposed based on the Chebyshev pseudo-spectral method for solving optimal control problems governed by Burgers’ equation. Pseudo-spectral methods are one of the most accurate methods for solving nonlinear continuous-time problems, specially optimal control problems. By using optimality conditions, the original optimal control problem is first reduced to a system of partial differential equations with boundary conditions. Control and state functions are then approximated by interpolating polynomials. The convergence is analyzed, and some numerical examples are solved to show the efficiency and capability of the method.Fri, 04 Oct 2019 20:30:00 +0100Differential transform method for conformable fractional partial differential equations
http://iranjournals.nlai.ir/2547/article_610348_83181.html
We expand a new generalization of the two-dimensional differential trans form method. The new generalization is based on the two-dimensional differential transform method, fractional power series expansions, and conformable fractional derivative. We use the new method for solving a nonlinear con formable fractional partial differential equation and a system of conformable fractional partial differential equation. Finally, numerical examples are presented to illustrate the preciseness and effectiveness of the new technique.Fri, 04 Oct 2019 20:30:00 +0100Fuzzy endpoint results for ´ Ciri´c-generalized quasicontractive fuzzy mappings
http://iranjournals.nlai.ir/2547/article_610349_83181.html
We introduce Ciri´c-generalized quasicontractive fuzzy mappings and pro vide the necessary and sufficient conditions of having a unique endpoint for such mappings. Then we introduce β-ψ-quasicontractive fuzzy mappings, es tablishing an endpoint result for them. Finally, we provide some results as an application.Fri, 04 Oct 2019 20:30:00 +0100A new regularization term based on second order total generalized variation for image denoising ...
http://iranjournals.nlai.ir/2547/article_610350_83181.html
Variational models are one of the most efficient techniques for image denoising problems. A variational method refers to the technique of optimizing a functional in order to restore appropriate solutions from observed data that best fit the original image. This paper proposes to revisit the discrete total generalized variation (TGV ) image denoising problem by redefining the operations via the inclusion of a diagonal term to reduce the staircasing effect, which is the patchy artifacts usually observed in slanted regions of the image. We propose to add an oblique scheme in discretization operators, which we claim is aware of the alleviation of the staircasing effect superior to the con ventional TGV method. Numerical experiments are carried out by using the primal-dual algorithm, and numerous real-world examples are conducted to confirm that the new proposed method achieves higher quality in terms of rel ative error and the peak signal to noise ratio compared with the conventional TGV method.Fri, 04 Oct 2019 20:30:00 +0100Approximate solution of a system of singular integral equations of the first kind by using ...
http://iranjournals.nlai.ir/2547/article_610351_83181.html
The aim of the present work is to introduce a method based on the Chebyshev polynomials for numerical solution of a system of Cauchy type singular integral equations of the first kind on a finite segment. Moreover, an estimation error is computed for the approximate solution. Numerical resultsdemonstrate the effectiveness of the proposed method.Fri, 04 Oct 2019 20:30:00 +0100Multicriteria allocation model of additional resources based on DEA: MOILP-DEA
http://iranjournals.nlai.ir/2547/article_610352_83181.html
We exploit the relationship between multiobjective integer linear problem (MOILP) and data envelopment analysis (DEA) to develop an approach to a resource reallocation problem. The general purpose of the mathematical formulation of this multicriteria allocation model based on DEA is to enable decision-makers to take into account the efficiency of units under control to allocate additional resources for a new period of operation. We develop a formal approach based on DEA and MOILP to find the most preferred allocation plan taken account additional resources. The mathematical model is given, and we illustrate it with a numerical example.Fri, 04 Oct 2019 20:30:00 +0100A new approximate inverse preconditioner based on the Vaidya’s maximum spanning tree for ...
http://iranjournals.nlai.ir/2547/article_610353_83181.html
We propose a new preconditioned global conjugate gradient (PGL-CG) method for the solution of matrix equation AXB = C, where A and B are sparse Stieltjes matrices. The preconditioner is based on the support graph preconditioners. By using Vaidya’s maximum spanning tree precon ditioner and BFS algorithm, we present a new algorithm for computing the approximate inverse preconditioners for matrices A and B and constructing a preconditioner for the matrix equation AXB = C. This preconditioner does not require solving any linear systems and is highly parallelizable. Numerical experiments are given to show the efficiency of the new algorithm on CPU and GPU for the solution of large sparse matrix equation.Fri, 04 Oct 2019 20:30:00 +0100An updated two-step method for solving interval linear programming: A case study of the air ...
http://iranjournals.nlai.ir/2547/article_610354_83181.html
Many real-world problems occur under uncertainty. In this paper, we consider interval linear programming (ILP) which can be used to tackle un certainties. Several methods have been proposed by researchers, such as the best and worst cases, Two-step method (TSM), improved TSM, ILP, improved ILP, three-step method, and robust two-step method. First, we define feasibility and optimality conditions in ILP models and review some solving methods shortly, and then show that some solutions of the TSM method are not feasible. Therefore, we propose an updated TSM method (namely, UTSM) by considering the feasibility and optimality conditions. In this paper, the UTSM method was applied to identify the reduction of aerosols by using two controllers with a minimized cost to demonstrate its application under uncertainty. Compared with other methods, the solutions obtained through ILP were presented as interval, which can provide intervals for the decision variables, objective function, and decision-makers. Therefore, the decision-makers can make the best decision based on the obtained solutionsthrough ILP, and then identify desired plans for aerosol-emission control under uncertainty.Fri, 04 Oct 2019 20:30:00 +0100A discrete orthogonal polynomials approach for fractional optimal control problems with time delay
http://iranjournals.nlai.ir/2547/article_610355_83181.html
An efficient direct and numerical method has been proposed to approximate a solution of time-delay fractional optimal control problems. First, a class of discrete orthogonal polynomials, called Hahn polynomials, has been introduced and their properties are investigated. These properties are employed to derive a general formulation of their operational matrix of fractional integration, in the Riemann–Liouville sense. Then, the fractional derivative of the state function in the dynamic constraint of time-delay fractional optimal control problems is approximated by the Hahn polynomials with unknown coefficients. The operational matrix of fractional integration together with the dynamical constraints is used to approximate the control function directly as a function of the state function. Finally, these approximations were put in the performance index and necessary conditions for optimality transform the under consideration time-delay fractional optimal control prob lems into an algebraic system. Some illustrative examples are given and the obtained numerical results are compared with those previously published in the literature.Fri, 04 Oct 2019 20:30:00 +0100Solving linear optimal control problems of the time-delayed systems by Adomian decomposition method
http://iranjournals.nlai.ir/2547/article_610356_83181.html
We apply the Adomian decomposition method (ADM) to obtain a subop timal control for linear time-varying systems with multiple state and control delays and with quadratic cost functional. In fact, the nonlinear two-point boundary value problem, derived from Pontryagin’s maximum principle, is solved by ADM. For the first time, we present here a convergence proof for ADM. In order to use the proposed method, a control design algorithm with low computational complexity is presented. Through the finite iterations of algorithm, a suboptimal control law is obtained for the linear time-varying multi-delay systems. Some illustrative examples are employed to demonstrate the accuracy and efficiency of the proposed methods.Fri, 04 Oct 2019 20:30:00 +0100Capturing outlines of generic shapes with cubic B´ezier curves using the Nelder–Mead simplex ...
http://iranjournals.nlai.ir/2547/article_610357_83181.html
We design a fast technique for fitting cubic B´ezier curves to the boundary of 2D shapes. The technique is implemented by means of the Nelder–Mead simplex procedure to optimize the control points. The natural attributes of the B´ezier curve are utilized to discover the initial vertex points of the Nelder–Mead procedure. The proposed technique is faster than traditional methods and helps to obtain a better fit with a desirable precision. The comparative analysis of our results describes that the introduced approach has a high compression ratio and a low fitting error.Fri, 04 Oct 2019 20:30:00 +0100