Loading...
Search for:
mahdavi--reza
0.137 seconds
Total 2442 records
Photo-induced CdS nanoparticles growth
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 30, Issue 1-2 , 2005 , Pages 114-119 ; 13869477 (ISSN) ; Azam Iraji Zad ; Mahdavi, S. M ; Reza-Esmaili, M ; Sharif University of Technology
2005
Abstract
A photochemical approach on the size control of CdS nanoparticles is presented. CdS nanoparticles were grown using the photo-induced reaction of sodium thiosulfate with Cadmium sulfate, in the absence of any surfactant. Particles of 5.5-11 nm were obtained by changing the illumination time. The dark growth of nanoparticles was negligible, however we found by optical scattering measurements that a ripening phenomenon occurs and the size of nanoparticles slightly increases with time. © 2005 Elsevier B.V. All rights reserved
Improving the Security of Private Set Intersectio
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Mohajeri, Javad (Co-Advisor)
Abstract
In some applications in the field of information technology such as social networks and medical databases in different hospitals, sometimes an entity needs to calculate the extent of its sharing of information documents with other institutions. Access to one entity's information is not possible due to the confidentiality of users' information. Therefore, in order to calculate common documents, users should be able to do so without revealing their private information. Therefore, it is required protocols such that can only obtain the shared information between two mentioned entities, while preserving the confidentiality of uncommon information. The schemes that meet the above objectives are...
Algorithms for Solving Fuzzy Linear and Quadratic Problems Directly and Duality Results for Bipolar Fuzzy Optimization Problems
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi Amiri, Nezameddin (Supervisor) ; Ghanbari, Reza (Co-Supervisor)
Abstract
There are many linear and nonlinear programming problems with uncertain parameters and variables. These types of linear and nonlinear models are called fuzzy linear and nonlinear programming problems. Solving such problems is important, due to applications and variety of these models. Here, we first review various types of fuzzy linear programming problems based on the models or the solution methods. Next, we revise a method due to Kerre to compare two unipolar LR fuzzy numbers and present some new results on the comparison of LR fuzzy numbers. Then, we solve linear programming problems with unipolar fuzzy numbers by our proposed time varient particle swarm optimization (TV-PSO) algorithm....
Light propagation and Localization in Inhomogeneous and Random Optical Waveguide Lattices
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Bahrampour, Ali Reza (Co-Advisor)
Abstract
Photonic lattices can provide an inexpensive and fine tools to investigate some common phenomena in condensed matter physics, quantum optics, relativistic mechanics,atomic and molecular physics. These phenomena contain Anderson localization,Bloch oscillation, Dynamic localization, coherent and squeezed states, Relativistic Dirac equation, Rabi oscillation, ... .In this thesis, it was investigated three worthy phenomena of them, which at first are introduced in condensed matter physics for electronic systems, in photonic lattices. These phenomena are as follow: Transverse localization of light wave, Bloch oscillation and dynamic localization of light. It was also simulate classically, the...
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 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
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...
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 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...
Numerical Simulation, Tunability and Experimental Investigation of Random Lasers and Using ZnO Nanosheets in these Lasers and UV Photodetectors
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Bahrampour, Ali Reza (Supervisor) ; Taghavinia, Nima (Co-Advisor)
Abstract
In this thesis, first, random lasing in a three dimensional disordered medium has been simulated using FDTD method and some properties of random lasers which were observed by others in the previous experiments have theoretically been shown. Our simulation results show that when the density of particles increases to an upper limit, the intensity of lasing modes is enhanced. Also, the effects of pumping rate and particle size on the number of lasing modes and their intensity are studied. Lasing threshold of laser modes in different disordered systems is calculated and it is shown that by an appropriate selection of the central frequency of gain line-shape, the output power intensity of random...
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...
Designing a new algorithm for the fuzzy shortest path problem in a network
, Article 37th International Conference on Computers and Industrial Engineering 2007, Alexandria, 20 October 2007 through 23 October 2007 ; Volume 1 , 2007 , Pages 556-563 ; 9781627486811 (ISBN) ; Tajdin, A ; Nourifar, R ; Hasanzade, R ; Mahdavi Amiri, N ; Sharif University of Technology
2007
Abstract
The shortest path problem is a classical and important network optimization problem appearing in many applications. We discuss the shortest path problem from a specified vertex to every other vertex on a network with imprecise arc lengths as fuzzy numbers. Using an order relation between fuzzy numbers, we propose a new algorithm to deal with the fuzzy shortest path problem. The algorithm is composed of a fuzzy shortest path length procedure and a similarity measure. The fuzzy shortest length method is proposed to find the fuzzy shortest length, and the fuzzy similarity measure is utilized to get the shortest path. Two illustrative examples are worked out to demonstrate the proposed algorithm...
A model for the time dependent vehicle routing problem with time windows under traffic conditions with intelligent travel times
, Article RAIRO - Operations Research ; Volume 55, Issue 4 , 2021 , Pages 2203-2222 ; 03990559 (ISSN) ; Shahmizad, M ; Mahdavi, I ; Mahdavi Amiri, N ; Ghasemi, P ; Sharif University of Technology
EDP Sciences
2021
Abstract
A new mixed-integer nonlinear programming model is presented for the time-dependent vehicle routing problem with time windows and intelligent travel times. The aim is to minimize fixed and variable costs, with the assumption that the travel time between any two nodes depends on traffic conditions and is considered to be a function of vehicle departure time. Depending on working hours, the route between any two nodes has a unique traffic parameter. We consider each working day to be divided into several equal and large intervals, termed as a time interval of traffic. Here, allowing for long distances between some of the nodes, travel time may take more than one time interval of traffic,...