Loading...
Search for:
mahdavi--e
0.103 seconds
Total 2752 records
A genetic algorithm for optimization problems with fuzzy relation constraints using max-product composition
, Article Applied Soft Computing Journal ; Volume 11, Issue 1 , 2011 , Pages 551-560 ; 15684946 (ISSN) ; Khorram, E ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
2011
Abstract
We consider nonlinear optimization problems constrained by a system of fuzzy relation equations. The solution set of the fuzzy relation equations being nonconvex, in general, conventional nonlinear programming methods are not practical. Here, we propose a genetic algorithm with max-product composition to obtain a near optimal solution for convex or nonconvex solution set. Test problems are constructed to evaluate the performance of the proposed algorithm showing alternative solutions obtained by our proposed model
Data envelopment analysis based comparison of two hybrid multi-criteria decision-making approaches for mobile phone selection: a case study in Iranian telecommunication environment
, Article International Journal of Information and Decision Sciences ; Volume 1, Issue 2 , 2008 , Pages 194-220 ; 17567017 (ISSN) ; Fazlollahtabar, H ; Mozaffari, E ; Heidari, M ; Mahdavi Amiri, N ; Sharif University of Technology
2008
Abstract
The arrival of the mobile phone and its rapid and widespread growth may well be seen as one of the most significant developments in the fields of communication and information technology over the past two decades. The aim of this study is to compare two hybrid multi-criteria decision-making (MCDM) approaches to evaluate the mobile phone options with respect to user’s preferences. Firstly, we identify the most desirable features influencing the choice of a mobile phone. This is realised through a survey conducted among the target group, the experiences of the telecommunication sector experts and the studies in the literature. Secondly, two MCDM methods are used in the evaluation procedure....
Extended rank reduction formulas containing Wedderburn and Abaffy-Broyden-Spedicato rank reducing processes
, Article Linear Algebra and Its Applications ; Volume 439, Issue 11 , 2013 , Pages 3318-3331 ; 00243795 (ISSN) ; Golpar Raboky, E ; Sharif University of Technology
2013
Abstract
The Wedderburn rank reduction formula and the Abaffy-Broyden-Spedicato (ABS) algorithms are powerful methods for developing matrix factorizations and many fundamental numerical linear algebra processes such as Gram-Schmidt, conjugate direction and Lanczos methods. We present a rank reduction formula for transforming the rows and columns of A, extending the Wedderburn rank reduction formula and the ABS approach. By repeatedly applying the formula to reduce the rank, an extended rank reducing process is derived. The biconjugation process associated with the Wedderburn rank reduction process and the scaled extended ABS class of algorithms are shown to be in our proposed rank reducing process,...
Real and integer Wedderburn rank reduction formulas for matrix decompositions
, Article Optimization Methods and Software ; Volume 30, Issue 4 , 2015 , Pages 864-879 ; 10556788 (ISSN) ; Golpar Raboky, E ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
The Wedderburn rank reduction formula is a powerful method for developing matrix factorizations and many fundamental numerical linear algebra processes. We present a new interpretation of the Wedderburn rank reduction formula and its associated biconjugation process and see a more extensive result of the formula. In doing this, we propose a new formulation based on the null space transformations on rows and columns of A simultaneously, and show several matrix factorizations that can be derived from the Wedderburn rank reduction formula. We also present a generalization of the biconjugation process and compute banded and Hessenberg factorizations. Using the new formulation, we compute the WZ...
An improved harmony search algorithm for solving optimization problems
, Article Applied Mathematics and Computation ; Volume 188, Issue 2 , 2007 , Pages 1567-1579 ; 00963003 (ISSN) ; Fesanghary, M ; Damangir, E ; Sharif University of Technology
2007
Abstract
This paper develops an Improved harmony search (IHS) algorithm for solving optimization problems. IHS employs a novel method for generating new solution vectors that enhances accuracy and convergence rate of harmony search (HS) algorithm. In this paper the impacts of constant parameters on harmony search algorithm are discussed and a strategy for tuning these parameters is presented. The IHS algorithm has been successfully applied to various benchmarking and standard engineering optimization problems. Numerical results reveal that the proposed algorithm can find better solutions when compared to HS and other heuristic or deterministic methods and is a powerful search algorithm for various...
Balancing public bicycle sharing system using inventory critical levels in queuing network
, Article Computers and Industrial Engineering ; Volume 141 , March , 2020 ; Mahdavi, I ; Mahdavi Amiri, N ; Khorram, E ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Public Bicycle Sharing System has recently been developed and installed in many cities as a workable and popular transportation system. There are still some noticeable challenges associated with the operation of the system, like responding to all renting requests and all demands of vacant docks for returning bikes. Balancing the inventory of stations is necessary to minimize the rejected demands of bikes and the empty lockers. Here, critical levels are defined to control requests of different routes in which a demand of a specified destination is accepted if the inventory of the original station is higher than the route's critical level. The capacity of stations and the fleet size are...
Heuristic Hybrid Genetic and Simulated Annealing Algorithms with Neural Networks for Task Assignment in Heterogeneous Computing Systems
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Amiri, Nezamoddin (Supervisor)
Abstract
In this thesis, we want to present methods that are able to solve the assignment tasks problem in a heterogeneous computing system. These methods are two hybrid methods that are constructed by composing Hopefield Neural Networks with Genetic Algorithms and the Simulated Annealing. First, we solve the relaxed problem by applying Genetic Algorithms and the Simulated Annealing and we compare the results of these ways with other traditional methods. Then, we solve the constrained problem with mentioned hybrid methods. The definition of the problem is as following: Consider a distributed computing system which is comprised of set of processors with different speeds but the same structure. We want...
A modified ant colony system for finding the expected shortest path in networks with variable arc lengths and probabilistic nodes
, Article Applied Soft Computing Journal ; Vol. 21, issue , August , 2014 , p. 491-500 ; Hassanzadeh, R ; Mahdavi, I ; Mahdavi-Amiri, N ; Sharif University of Technology
2014
Abstract
The problem of finding the expected shortest path in stochastic networks, where the presence of each node is probabilistic and the arc lengths are random variables, have numerous applications, especially in communication networks. The problem being NP-hard we use an ant colony system (ACS) to propose a metaheuristic algorithm for finding the expected shortest path. A new local heuristic is formulated for the proposed algorithm to consider the probabilistic nodes. The arc lengths are randomly generated based on the arc length distribution functions. Examples are worked out to illustrate the applicability of the proposed approach
A genetic optimization algorithm and perceptron learning rules for a bi-criteria parallel machine scheduling
, Article Journal of the Chinese Institute of Industrial Engineers ; Volume 29, Issue 3 , 2012 , Pages 206-218 ; 10170669 (ISSN) ; Hassanzadeh, R ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
2012
Abstract
This work considers scheduling problems minding the setup and removal times of jobs rather than processing times. For some production systems, setup times and removal times are so important to be considered independent of processing times. In general, jobs are performed according to the automatic machine processing in production systems, and the processing times are considered to be constant regardless of the process sequence. As the human factor can influence the setup and removal times, when the setup process is repetitive the setup times decreases. This fact is considered as learning effect in scheduling literature. In this study, a bi-criteria m-identical parallel machines scheduling...
A DEA approach for comparing solution efficiency in U-line balancing problem using goal programming
, Article International Journal of Advanced Manufacturing Technology ; Volume 61, Issue 9-12 , August , 2012 , Pages 1161-1172 ; 02683768 (ISSN) ; Hassanzadeh, R ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
Springer
2012
Abstract
Line balancing problem plays an important role in the decision making process to increase efficiency and productivity. Recently, U-shaped layout in many production lines has replaced the traditional straight line layout using just-in-time concept. Here, we propose a model, using multi-objective decision making approach to the U-shaped line balancing problem, to offer enhanced decision maker flexibility, by allowing for conflicting goals. The assembly line operation efficiency is the most significant aim in our study, and this efficiency relates to management of resources and the solution of line balancing problem. First, the U-shaped line balancing problem is solved considering the model's...
A dynamic programming approach for finding shortest chains in a fuzzy network
, Article Applied Soft Computing Journal ; Volume 9, Issue 2 , 2009 , Pages 503-511 ; 15684946 (ISSN) ; Nourifar, R ; Heidarzade, A ; Mahdavi Amiri, N ; Sharif University of Technology
2009
Abstract
Graph theory has numerous applications to problems in systems analysis, operations research, transportation, and economics. In many cases, however, some aspects of a graph-theoretic problem may be uncertain. For example, the vehicle travel time or vehicle capacity on a road network may not be known exactly. In such cases, it is natural to make use of fuzzy set theory to deal with the uncertainty. Here, we are concerned with finding shortest chains in a graph with fuzzy distance for every edge. We propose a dynamic programming approach to solve the fuzzy shortest chain problem using a suitable ranking method. By using MATLAB, two illustrative examples are worked out to demonstrate the...
A two-phase linear programming methodology for fuzzy multi-objective mixed-model assembly line problem
, Article International Journal of Advanced Manufacturing Technology ; Volume 44, Issue 9-10 , 2009 , Pages 1010-1023 ; 02683768 (ISSN) ; Javadi, B ; Sahebjamnia, N ; Mahdavi Amiri, N ; Sharif University of Technology
2009
Abstract
We develop a fuzzy multi-objective linear programming (FMOLP) model for solving multi-objective mixed-model assembly line problem. In practice, vagueness and imprecision of the goals in this problem make the fuzzy decision-making complicated. The proposed model considers minimizing total utility work, total production rate variation, and total setup cost, using a two-phase linear programming approach. In the first phase, the problem is solved using a max-min approach. The max-min solution not being efficient, in general, we propose a new model in the second phase to maximize a composite satisfaction degree at least as good as the degrees obtained by phase one. To show the effectiveness of...
Reserve capacity of mixed urban road networks, network configuration and signal settings
, Article Intelligent Transportation and Planning: Breakthroughs in Research and Practice ; February , 2018 , Pages 883-906 ; 9781522552116 (EISBN) ; Hassanzadeh, R ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
IGI Global
2018
Abstract
The authors formulate the transportation mixed network design problem (MNDP) as a mixed-integer bi-level mathematical problem, based on the concept of reserve capacity. The upper level goal is to maximize the reserve capacity by signal settings at intersections, determine street direction and increase street capacities via addition of lanes. The lower level problem is a deterministic user equilibrium traffic assignment problem to minimize the user travel time. The model being non-convex, meta-heuristic methods are used to solve the problem. A hybridization of genetic algorithm with simulated annealing and a bee algorithm are proposed. Numerical examples are illustrated to verify the...
Toward sustainable optimization with stackelberg game between green product family and downstream supply chain
, Article Sustainable Production and Consumption ; Volume 23 , 2020 , Pages 198-211 ; Shirazi, B ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Green products are increasingly considered by companies, owing to the significant attention of government regulations, customers’ requests and competitors. Here, we deal with Green Product Families (GPFs) by selecting green components, modules and products which are produced based on the assembling to order (ATO) approach to cover diverse customer needs. Designing a GPFs is important but not sufficient for sustainable optimization. In fact, we need to simultaneously consider the supply chain of a GPF to control the pollution generated in the downstream supply chain. For a sustainable optimization approach, this joint configuration is usually structured based on economic, environmental and...
Thermo-mechanical analysis of rotating disks with non-uniform thickness and material properties
, Article International Journal of Pressure Vessels and Piping ; Volume 98 , October , 2012 , Pages 95-101 ; 03080161 (ISSN) ; Hojjati, M. H ; Mahdavi, E ; Alashti, R. A ; Farrahi, G ; Sharif University of Technology
Elsevier
2012
Abstract
Theoretical and numerical analyses of rotating disks with non-uniform thickness and material properties subjected to thermo-mechanical loadings have been carried out by variable material properties (VMP), Runge-Kutta's (RK) and finite element (FE) methods. The material is assumed to be elastic-linear hardening. A power form function is used to describe the temperature gradient with the higher temperature at outer surface. Von-Mises theory has been used as failure criterion. The effects of geometry, material and thermal loading parameters as well as boundary conditions on radial, hoop and equivalent stress distributions which have not been studied in much detail in previous works have been...
A general fuzzy TOPSIS model in multiple criteria decision making
, Article International Journal of Advanced Manufacturing Technology ; Volume 45, Issue 3-4 , 2009 , Pages 406-420 ; 02683768 (ISSN) ; Heidarzade, A ; Sadeghpour Gildeh, B ; Mahdavi Amiri, N ; Sharif University of Technology
2009
Abstract
Decision making is the process of finding the best option among the feasible alternatives. In classical multiple criteria decision-making (MCDM) methods, the ratings and the weights of the criteria are known precisely. Owning to vagueness of the decision data, the crisp data are inadequate for real-life situations. Since human judgments including preferences are often vague and cannot be expressed by exact numerical values, the application of fuzzy concepts in decision making is deemed to be relevant. In this paper, we proposed the application of a fuzzy distance formula in order to compute a crisp value for the standard deviation of fuzzy data. Then, we use this crisp value of the standard...
A comprehensive fuzzy TOPSIS model in multiple criteria decision making
, Article 37th International Conference on Computers and Industrial Engineering 2007, Alexandria, 20 October 2007 through 23 October 2007 ; Volume 1 , 2007 , Pages 537-548 ; 9781627486811 (ISBN) ; Sadeghpour Gildeh, B ; Heidarzade, A ; Mahdavi Amiri, N ; Sharif University of Technology
2007
Abstract
Decision making is the process of finding the best option among the feasible alternatives. In classical multiple criteria decision making (MCDM) methods, the ratings and the weights of the criteria are known precisely. Owning to vagueness of the decision data, the crisp data are inadequate for real-life situations. Since human judgments including preferences are often vague and cannot be expressed by exact numerical values, the application of fuzzy concepts in decision making is deemed to be relevant. Here, we apply a new distance formula to compute the standard deviation of fuzzy data to achieve crisp data by normalization. There is a flexibility to consider various fuzzy values as...
Sb2S3 and Cu3SbS4 nanocrystals as inorganic hole transporting materials in perovskite solar cells
, Article Solar Energy ; Volume 223 , 2021 , Pages 106-112 ; 0038092X (ISSN) ; Heidariramsheh, M ; Javadpour, S ; Ghavaminia, E ; Mahdavi, S. M ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
One of the key parts of perovskite solar cells which has great influence on their performance and stability is hole transporting layer. Spiro-OMeTAD is extensively used as organic hole transporting material in perovskite solar cells. However, Spiro-OMeTAD is expensive and has low chemical stability. In this study, the solution processed Sb2S3 and Cu3SbS4 nanocrystals have been synthesized and then the n-i-p mesoscopic perovskite solar cells have been fabricated using Spiro-OMeTAD, Sb2S3 and Cu3SbS4 nanocrystals as hole transporting layer at ambient air condition. It is shown that the conduction and valence band levels of the synthesized Sb2S3 and Cu3SbS4 nanocrystals are in the proper...
Genetic algorithm for solving fuzzy shortest path problem in a network with mixed fuzzy arc lengths
, Article AIP Conference Proceedings, 2 December 2010 through 4 December 2010, Sarawak ; Volume 1337 , 2011 , Pages 265-270 ; 0094243X (ISSN) ; 9780735408937 (ISBN) ; Tajdin, A ; Hassanzadeh, R ; Mahdavi-Amiri, N ; Shafieian, H ; Sharif University of Technology
2011
Abstract
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 linear least squares model to obtain membership functions for the considered additions. Then, using a recently proposed distance function for comparison of fuzzy numbers. we propose a new approach to solve the fuzzy APSPP using of genetic algorithm. Examples are worked out to illustrate the applicability of the proposed model
Agent-based web service for the design of a dynamic coordination mechanism in supply networks
, Article Journal of Intelligent Manufacturing ; Volume 20, Issue 6 , 2009 , Pages 727-749 ; 09565515 (ISSN) ; Mohebbi, S ; Zandakbari, M ; Cho, N ; Mahdavi Amiri, N ; Sharif University of Technology
2009
Abstract
The theory of network coordination presents an effective approach to improve the business processes within supply networks. The automation of the negotiation process among buyers and suppliers has become an important policy in the transactional networks. This leads to assessing the roles of both quantifiable and non-quantifiable parameters in coordination mechanisms with the aim of achieving higher performance. Here, we develop an e-based supply chain multi-agent model for the design of mass-customized on-line services. The model addresses the bullwhip effect in multi-stage supply chain and also clarifies the evaluation of inventory policies in various supply and demand uncertainties. To...