Papers by Nezam Mahdavi-Amiri
Journal of Industrial and Management Optimization, 2022
We consider a median location problem in the presence of two probabilistic line barriers on the p... more We consider a median location problem in the presence of two probabilistic line barriers on the plane under rectilinear distance. It is assumed that the two line barriers move on their corresponding horizontal routes uniformly. We first investigate different scenarios for the position of the line barriers on the plane and their corresponding routes, and then define the visibility and invisibility conditions along with their corresponding expected barrier distance functions. The proposed problem is formulated as a mixed-integer nonlinear programming model. Our aim is to locate a new facility on the plane so that the total weighted expected rectilinear barrier distance is minimized. We present efficient lower and upper bounds using the forbidden location problem for the proposed problem. To solve the proposed model, the Hooke and Jeeves algorithm (HJA) is extended. We investigate various sample problems to test the performance of the proposed algorithm and appropriateness of the bounds. Also, an empirical study in Kingston-upon-Thames, England, is conducted to illustrate the behavior and applicability of the proposed model.
Bulletin of The Iranian Mathematical Society, Sep 16, 2019
Abaffy, Broyden and Spediacto (ABS) introduced a class of the so-called ABS methods to solve syst... more Abaffy, Broyden and Spediacto (ABS) introduced a class of the so-called ABS methods to solve systems of linear equations. The ABS approach was specialized to solve linear Diophantine systems by Esmaeili, Mahdavi-Amiri and Spedicato. The method was extended to systems of certain linear inequalities to provide all solutions. Here, we mainly focus on the theoretical research into rank reduction processes for solving linear Diophantine systems and computing integer factorizations. Basic integer ABS algorithm, integer extended ABS (IEABS) algorithm, rank one perturbed problem, the generalized Rosser's approach (GRA), the extended integer rank reduction process, the integer Wedderburn rank reduction formula and the associated integer biconjugation process are studied. We present an integrated integer rank reduction process, develop various integer factorizations and show their use in solving Diophantine equations. Linear Diophantine systems • Matrix decomposition • Scaled extended integer ABS algorithms • Extended integer rank reduction formula • Smith normal form Mathematics Subject Classification 15A03 • 15A23 • 15A63 • 34C20 1 Introduction ABS methods comprise an extensive class of algorithms, first introduced by Abaffy, Broyden and Spedicato, for solving linear systems of equations, and later extended Communicated by Davod Khojasteh Salkuyeh.
Lot streaming in a two-stage assembly hybrid flow shop scheduling problem with a work shift constraint
Journal of Industrial and Production Engineering, Feb 19, 2016
We address the two-stage assembly scheduling problem where there are m machines at the first stag... more We address the two-stage assembly scheduling problem where there are m machines at the first stage and n assembly machines at the second stage under lot sizing environment. Lot streaming (lot sizing) means breaking a lot into some sublots, where each sublot is transferred to the next machine for continuing operations. This problem can be considered as a production system model consisting of production stage and assembly stage. If different production operations are done in parallel machines independently, then the manufactured parts transferred to the next stage are assembled with purchased parts at n machines according to the operation process chart to produce the final products. Here, work-in-process inventories, work shifts, and sequence-dependent setup times are also considered as three important presumptions in order to make the problem more realistic. The objective is to minimize the sum of weighted completion times of products in each shift in order to furnish better machine utilization for the next shifts. In recent years, much effort has been made to develop good heuristics and search techniques. We propose a genetic algorithm and simulated annealing to compute the best sequence and scheduling for a two-stage assembly hybrid flow shop problem. Our numerical results demonstrate the effectiveness of the presented model and the proposed solution approach.
arXiv (Cornell University), Mar 11, 2018
We are to establish necessary conditions (of the primal and dual types) for the set of weak sharp... more We are to establish necessary conditions (of the primal and dual types) for the set of weak sharp minima of a nonconvex optimization problem on a Riemannian manifold. Here, we are to provide a generalization of some characterizations of weak sharp minima for convex problems on Riemannian manifold introduced by Li et al. (SIAM J. Optim., 21 (2011), pp. 1523-1560) for nonconvex problems. We use the theory of the Fréchet and limiting subdifferentials on Riemannian manifold to give the necessary conditions of the dual type. We also consider a theory of contingent directional derivative and a notion of contingent cone on Riemannian manifold to give the necessary conditions of the primal type. Several definitions have been provided for the contingent cone on Riemannian manifold. We show that these definitions, with some modifications, are equivalent. We establish a lemma about the local behavior of a distance function. Using the lemma, we express the Fréchet subdifferential (contingent directional derivative) of a distance function on a Riemannian manifold in terms of normal cones (contingent cones), to establish the necessary conditions. As an application, we show how one can use weak sharp minima property to model a Cheeger type constant of a graph as an optimization problem on a Stiefel manifold.
Zenodo (CERN European Organization for Nuclear Research), May 17, 2023
Iranian journal of operations research, 2017
Bulletin of The Iranian Mathematical Society, Dec 18, 2016
and the Iranian Mathematical Society (IMS). UT [3] is the oldest and largest university in Iran. ... more and the Iranian Mathematical Society (IMS). UT [3] is the oldest and largest university in Iran. It is the symbol of higher education in Iran. The School of Mathematics, Statistics and Computer Science of UT is also the oldest Iranian higher education center in mathematics. Operations Research and Optimization are currently two of the most promising and active research areas of this school. The IPM [4] is an Iranian institute, founded in 1989 under the name "Institute for Studies in Theoretical Physics and Mathematics (IPM)". Its goal has been the advancement of research and innovation in theoretical physics and mathematics. The main activity of the IPM is to foster the culture of research all across the country. In recent years, mathematical optimization has become an active field at the IPM. GUAT [5], founded in 2007, is an advanced research center and a graduatelevel degree-granting institution in Kerman, Iran. Optimization is one of the most active fields at the Faculty of Science and Modern Technologies at GUAT. IMS [6] was officially registered in 1971 as a non-governmental and non-profit scientific organization, with the purpose of promoting national cooperation in mathematics. At present the IMS has about 700 full members, 2000 associate members and 45 institutional members. In addition, several outstanding overseas Iranian mathematicians are its honorary members. During the past 45
Strategic Development and SWOT Analysis for IT/ICT Programs in Universities of Mazandaran in Iran Using Digital Indices
Journal of Digital Convergence, 2009
The rapid growth of information and communication technologies prompted the need for developing t... more The rapid growth of information and communication technologies prompted the need for developing the strategic implementation framework of IT/ICT programs in universities. Here, we propose a strategic framework for the development of the IT/ICT programs in the universities of the province of Mazandaran in Iran. We use the SWOT analysis to assist the formulation of the strategy, where the Analytic Hierarchy Process (AHP) is applied to weigh the SWOT factors and the fuzzy TOPSIS is used to evaluate the strategic plans. Based on Iran and Mazandaran Digital Indices (DI) and considering the SWOT matrix, four strategies are identified. Finally, an analytical concept, namely the strategy shooting, is considered to show the role of SWOT factors and strategic plans on the performance of the system.
International Journal of Mathematics in Operational Research, 2018
We propose an approach for computing the product of various fuzzy numbers using α-cuts. A regress... more We propose an approach for computing the product of various fuzzy numbers using α-cuts. A regression model is used to obtain the membership function of the product. Then, we make use of the approach to compute solutions of fully fuzzy linear systems. We also show how to compute solutions of fully fuzzy linear systems with various fuzzy variables. Examples are worked out to illustrate the approach.
Genetic Algorithm for Solving Fuzzy Shortest Path Problem in a Network with mixed fuzzy arc lengths
Nucleation and Atmospheric Aerosols, 2011
[bold We are concerned with the design of a model and an algorithm for computing a shortest path ... more [bold We are concerned with the design of a model and an algorithm for computing a shortest path in a network having various types of fuzzy arc lengths. First, we develop a new technique for the addition of various fuzzy numbers in a path using α‐cuts by proposing a ...
A full Nesterov-Todd (NT) step infeasible interior-point algorithm is proposed for solving monoto... more A full Nesterov-Todd (NT) step infeasible interior-point algorithm is proposed for solving monotone linear complementarity problems over symmetric cones by using Euclidean Jordan algebra. Two types of full NT-steps are used, feasibility steps and centering steps. The algorithm starts from strictly feasible iterates of a perturbed problem, and, using the central path and feasibility steps, finds strictly feasible iterates for the next perturbed problem. By using centering steps for the new perturbed problem, strictly feasible iterates are obtained to be close enough to the central path of the new perturbed problem. The starting point depends on two positive numbers ρp and ρ d. The algorithm terminates either by finding an ϵ-solution or detecting that the symmetric cone linear complementarity problem has no optimal solution with vanishing duality gap satisfying a condition in terms of ρp and ρ d. The iteration bound coincides with the best known bound for infeasible interior-point methods.
A robust optimization model for dynamic virtual hub location problem under uncertainty using an M/M/C/K queuing model: two metaheuristic algorithms
Operational Research, Jun 10, 2023
Time-varying dual accelerated gradient ascent: A fast network optimization algorithm
Journal of Parallel and Distributed Computing, Jul 1, 2022
Optimizing Employment and learning system using big data and knowledge management based on deduction graph
JITAM, Sep 1, 2016
Strategic Development and SWOT Analysis for IT/ICT Programs in Universities of
디지털융복합연구, Mar 1, 2009
원문정보. ...
Computer Aided Geometric Design, Feb 1, 2017
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • We extend diagrammatic approaches to construct multiresolution for semiregular meshes with extraordinary vertices and examine our technique for √ 3 subdivision in detail. • We provide indications that our proposed approach for √ 3 subdivision is potentially useful for other primal subdivision schemes by mentioning results for the Loop and Catmull-Clark subdivisions. • We analyze the quality of the reversal matrix and present a technique using numerical optimization.
Multi-class segmentation of skin lesions via joint dictionary learning
Biomedical Signal Processing and Control, Jul 1, 2021
4OR, May 6, 2019
We present an algorithm for minimizing locally Lipschitz functions being continuously differentia... more We present an algorithm for minimizing locally Lipschitz functions being continuously differentiable in an open dense subset of R n. The function may be nonsmooth and/or nonconvex. The method makes use of a gradient sampling method along with a conjugate gradient scheme. To find search directions, we make use of a sequence of positive definite approximate Hessians based on conjugate gradient matrices. The algorithm benefits from a restart procedure to improve upon poor search directions or to make sure that the approximate Hessians remain bounded. The global convergence of the algorithm is established. An implementation of the algorithm is executed on a collection of well-known test problems. Comparative numerical results clearly show outperformance of the algorithm over some recent well-known nonsmooth algorithms using the Dolan-Moré performance profiles.
Computational Intelligence, Dec 1, 2019
Today, organizations try to decline academically expenses using humans and resources in addition ... more Today, organizations try to decline academically expenses using humans and resources in addition to rising managers and operators' satisfaction. Meantime, a very important step in the process of decision is the assignment of human resources, particularly in connection with research and development (R&D) projects in which the system is highly dependent on the capabilities of human resources. In this study, we tried all the assumptions that come true in the real world, considered a model for applied R&D projects to reduce costs and increase the efficiency of projects. Therefore, an integrated multiproject scheduling and multiskill human resource assignment model under uncertainty has developed for R&D projects. Furthermore, it is assumed that the activity processing time is related to human resources assignment that means the learning effect is considered. To demonstrate the proposed model efficiency, the various dimensions instance problem was solved accurately and efficiently in GAMS software, and the results have been reported. In addition, the proposed model is validated through the input parameter sensitivity analysis. The results indicate a suitable performance
Computer Methods and Programs in Biomedicine, Dec 1, 2019
Background and Objectives: Melanoma is a dangerous kind of skin disease with a high death rate, a... more Background and Objectives: Melanoma is a dangerous kind of skin disease with a high death rate, and its prevalence has increased rapidly in recent years. Diagnosis of melanoma in a primary phase can be helpful for its cure. Due to costs for dermatology, we need an automatic system to diagnose melanoma through lesion images. Methods: Here, we propose a sparse representation based method for segmentation and classification of lesion images. The main idea of our framework is based on a kernel sparse representation, which produces discriminative sparse codes to represent features in a high-dimensional feature space. Our novel formulation for discriminative kernel sparse coding jointly learns a kernel-based dictionary and a linear classifier. We also present an adaptive K-SVD algorithm for kernel dictionary and classifier learning. Results: We test our approach for both segmentation and classification tasks. The evaluation results on both dermoscopic and digital datasets demonstrate our approach to be competitive as compared to the available state-of-the-art methods, with the advantage of not needing any pre-processing. Conclusions: Our method is insensitive to noise and image conditions and can be used effectively for challenging skin lesions. Our approach is so extensive to be adapted to various medical image segmentations.
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Papers by Nezam Mahdavi-Amiri