Search for: multi-objective
Total 251 records
Article Journal of Industrial Engineering International ; Volume 14, Issue 1 , 2018 , Pages 111-118 ; 17355702 (ISSN) ; Mahdavi Amiri, N ; Fazlollahtabar, H ; Sharif University of Technology
A utility function is an important tool for representing a DM’s preference. We adjoin utility functions to multi-objective optimization problems. In current studies, usually one utility function is used for each objective function. Situations may arise for a goal to have multiple utility functions. Here, we consider a constrained multi-objective problem with each objective having multiple utility functions. We induce the probability of the utilities for each objective function using Bayesian theory. Illustrative examples considering dependence and independence of variables are worked through to demonstrate the usefulness of the proposed model. © 2017, The Author(s)
Article International Journal of Industrial Engineering Computations ; Volume 1, Issue 1 , 2010 , Pages 73-78 ; 19232926 (ISSN) ; Taghipour, T ; Jalali Farahani, K ; Sharif University of Technology
When a production facility is designed, there are various parameters affecting the number machines such as production capacity and reliability. It is often a tedious task to optimize different objectives, simultaneously. The other issue is the uncertainty in many design parameters which makes it difficult to reach a desirable solution. In this paper, we present a new mathematical model with two objectives. The primary objective function is considered to be the production capacity and the secondary objective function is total reliability. The proposed model is formulated on different units of production which are connected together in serial form and for each unit, we may have various...
Article Iranian Journal of Fuzzy Systems ; Volume 6, Issue 3 , 2009 , Pages 17-35 ; 17350654 (ISSN) ; Maali, Y ; Mahdavi Amiri, N ; Sharif University of Technology
We present a new model and a new approach for solving fuzzy linear programming (FLP) problems with various utilities for the satisfaction of the fuzzy constraints. The model, constructed as a multi-objective linear programming problem, provides flexibility for the decision maker (DM), and allows for the assignment of distinct weights to the constraints and the objective function. The desired solution is obtained by solving a crisp problem controlled by a parameter. We establish the validity of the proposed model and study the effect of the control parameter on the solution. We also illustrate the efficiency of the model and present three algorithms for solving the FLP problem, the first of...
A bi-objective model for scheduling of multiple projects under multi-skilled workforce for distributed load energy usage, Article Operational Research ; 2021 ; 11092858 (ISSN) ; Afshar Nadjafi, B ; Taghi Akhavan Niaki, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH 2021
Satisfying the clients' uncompromising priorities is a challenge for decision makers of organizations that face multiple projects. This paper considers an organization with a multi-skilled workforce working on several predetermined projects under time-of-use energy tariffs where distributed load energy usage is the primary concern of energy suppliers. This paper also considers different time-of-use energy tariffs, which are among the most common strategies to reach a more balanced energy utilization. The problem is stated as a bi-objective mixed-integer programming model containing two conflicting objectives; to minimize the total cost of the multi-skilled workforce and obtain a sustainable...
Thermoeconomic analysis and multi-objective optimization of an integrated solar system for hydrogen production using particle swarm optimization algorithm, Article Journal of Thermal Engineering ; Volume 7, Issue 4 , 2021 , Pages 746-760 ; 21487847 (ISSN) ; Assareh, E ; Moltames, R ; Taghipour, A ; Barati, H ; Sharif University of Technology
Yildiz Technical University 2021
This study aims to investigate the hydrogen production process using an integrated system based on solar energy. This system includes an evacuated tube collector to absorb solar energy as input energy of the system. A parametric analysis was conducted to determine the most important design parameters and evaluate these parameters' impact on the system's objective functions. For identifying the optimum system conditions, multi-objective optimization was performed using particle swarm optimization (PSO) algorithm. The results obtained from the parametric analysis show that an increment in the collector mass flow rate and the turbine inlet temperature, as well as a decrement in the collector...
M.Sc. Thesis Sharif University of Technology ; Eshghi, Kourosh
Real-world decision-making problems usually have several criteria for evaluating the performance of alternatives. On the other hand, mathematical programming is a very practical tool for modeling and solving decision-making problems and multi-objective mathematical programming has high importance among researchers and managers in this field of study. However, the field of multi-objective integer programming is considered a rigorous category. Methods for solving these types of problems can be divided into three different approaches. There are few approaches and methods for solving multi-objective mixed-integer optimization problems in litreture.In this research, an extension of benders...
A bi-objective integrated procurement, production, and distribution problem of a multi-echelon supply chain network design: A new tuned MOEA, Article Computers and Operations Research ; Volume 54 , February , 2014 , Pages 35-51 ; ISSN: 03050548 ; Rahmati,S. H. A ; Niaki, S. T. A ; Zaretalab, A ; Sharif University of Technology
Efficient management of supply chain (SC) requires systematic considerations of miscellaneous issues in its comprehensive version. In this paper, a multi-periodic structure is developed for a supply chain network design (SCND) involving suppliers, factories, distribution centers (DCs), and retailers. The nature of the logistic decisions is tactical that encompasses procurement of raw materials from suppliers, production of finished product at factories, distribution of finished product to retailers via DCs, and the storage of raw materials and end product at factories and DCs. Besides, to make the structure more comprehensive, a flow-shop scheduling model in manufacturing part of the SC is...
Article Annual Conference of the North American Fuzzy Information Processing Society - NAFIPS, 12 July 2010 through 14 July 2010 ; July , 2010 ; 9781424478576 (ISBN) ; Nikkholgh, R ; Gharahkozli, H ; Sharif University of Technology
This research deals with a model with better efficiency for selection of portfolio making use of cardinal constraints, which are explained in previous sections. Such a method, which is a combination of fuzzy models and MCDM considering the constraints intended by investors, has not been used in previous models. We have considered transactions cost, because they are among factors important for an investor, and their being ignored in a portfolio selection method will result in inefficient portfolio. Sector value constraint is among other constraints considered here. Such a constraint aims to raise investment rate in sectors with higher values. Cardinal constraints (number of shares existing in...
Article 2nd Conference on Swarm Intelligence and Evolutionary Computation, CSIEC 2017, 7 March 2017 through 9 March 2017 ; 2017 , Pages 60-65 ; 9781509043293 (ISBN) ; Bighashdel, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2017
In this paper, an extension of the recently developed Crow Search Algorithm (CSA) to multi-objective optimization problems is presented. The proposed algorithm, called Multi-Objective Crow Search Algorithm (MOCSA), defines the fitness function using a set of determined weight vectors, employing the max-min strategy. In order to improve the efficiency of the search space, the performance space is regionalized using specific control points. A new chasing operator is also employed in order to improve the convergence process. Numerical results show that MOCSA is closely comparable to well-known multi-objective algorithms. © 2017 IEEE
Optimizing a bi-objective multi-product EPQ model with defective items, rework and limited orders: NSGA-II and MOPSO algorithms, Article Journal of Manufacturing Systems ; Volume 32, Issue 4 , 2013 , Pages 764-770 ; 02786125 (ISSN) ; Niaki, S. T. A ; Sharafzadeh, S ; Sharif University of Technology
In this paper, a bi-objective multi-products economic production quantity (EPQ) model is developed, in which the number of orders is limited and imperfect items that are re-workable are produced. The objectives of the problem are minimization of the total inventory costs as well as minimizing the required warehouse space. The model is shown to be of a bi-objective nonlinear programming type, and in order to solve it two meta-heuristic algorithms namely, the non-dominated sorting genetic algorithm (NSGA-II) and multi-objective particle swarm optimization (MOPSO) algorithm, are proposed. To verify the solution obtained and to evaluate the performance of proposed algorithms, two-sample t-tests...
Multi-skilled project scheduling with level-dependent rework risk; three multi-objective mechanisms based on cuckoo search, Article Applied Soft Computing Journal ; Volume 54 , 2017 , Pages 46-61 ; 15684946 (ISSN) ; Afshar Nadjafi, B ; Akhavan Niaki, S. T ; Sharif University of Technology
Elsevier Ltd 2017
In many projects, multi-skilled workforces are able to perform different tasks with different quality levels. In this paper, a real-life version of the multi-skilled resource constrained project scheduling problem is investigated, in which the reworking risk of each activity depends on the assigned level of multi-skilled workforces. The problem is formulated mathematically as a bi-objective optimization model to minimize total costs of processing the activities and to minimize reworking risks of the activities, concurrently. In order to solve the resulting problem, three cuckoo-search-based multi-objective mechanisms are developed based on non-dominance sorting genetic algorithm,...
A robust optimization approach for multi-objective, multi-product, multi-period, closed-loop green supply chain network designs under uncertainty and discount, Article Journal of Industrial and Production Engineering ; Volume 37, Issue 1 , 2020 , Pages 1-22 ; Pasandideh, S. H. R ; Akhavan Niaki, S. T ; Sharif University of Technology
Taylor and Francis Ltd 2020
One of the basic requirements of the companies to survive in real-world competitive environments is to make their supply chains as efficient as possible. Due to recent governmental regulations, environmental issues, and the development of the concept of social responsibility, the closed-loop supply chain management has been focused by many researchers. A closed-loop supply chain includes both forward and reverse supply chain networks with the purpose of combining environmental considerations with the traditional supply chain network designs through the collection of used products and activities related to their reuse. In this paper, a bi-objective, multi-period, multi-product, closed-loop...
Article Journal of the Franklin Institute ; Volume 345, Issue 5 , August , 2008 , Pages 452-467 ; 00160032 (ISSN) ; Saidi Mehrabad, M ; Haji, A ; Mahdavi, I ; Jolai, F ; Mahdavi Amiri, N ; Sharif University of Technology
This study develops a fuzzy multi-objective linear programming (FMOLP) model for solving the multi-objective no-wait flow shop scheduling problem in a fuzzy environment. The proposed model attempts to simultaneously minimize the weighted mean completion time and the weighted mean earliness. A numerical example demonstrates the feasibility of applying the proposed model to no-wait flow shop scheduling problem. The proposed model yields a compromised solution and the decision maker's overall levels of satisfaction. © 2008 The#Franklin#Institute
A Multi-Objective Robust Optimization Model for Logistics Planning in the Earthquake Response Phase [electronic resource], Article Transportation Research Part E: Logistics and Transportation Review, Elsevier ; Volume 49, Issue 1, January 2013, , Pages 217–249 ; Eshghi, Kourosh ; Dullaert, Wout ; Sharif University of Technology
Usually, resources are short in supply when earthquakes occur. In such emergency situations, disaster relief organizations must use these scarce resources efficiently to achieve the best possible emergency relief. This paper therefore proposes a multi-objective, multi-mode, multi-commodity, and multi-period stochastic model to manage the logistics of both commodities and injured people in the earthquake response. Also, a robust approach is developed and used to make sure that the distribution plan performs well under the various situations that can follow an earthquake. Afterwards, it proposes a solution methodology according to hierarchical objective functions and uses it to illustrate the...
Multi-objective optimization approach for green design of methanol plant based on CO2-efficeincy indicator, Article Journal of Cleaner Production ; 2014 ; ISSN: 09596526 ; Pishvaie, M. R ; Farhadi, F ; Sharif University of Technology
The aim of the present work is to propose an eco-design method for sustainable development of methanol production by implementing a multi-objective optimization model based on CO2-efficiency. Two different approaches for the methanol production, i.e. a conventional reference methanol case (RMC) and proposed green integrated methanol case (GIMC) were compared from the view point of eco-design. Using life cycle assessment and process simulation, the environmental features as well as operational decision variables of the RMC and GIMC were assessed. Based on the inventory analysis of LCA, it was found that carbon dioxide is the major emitted pollutant from methanol production. Thus the...
Article International Review on Modelling and Simulations ; Volume 6, Issue 2 , April , 2013 , Pages 490-497 ; 19749821 (ISSN) ; Hamidi, M ; Farahmand, K ; Aghatehrani, R ; Sharif University of Technology
This article proposes a multi-objective goal programming based approach with two objectives of maximizing the reliability and minimizing the placement cost of Phasor Measurement Units (PMUs) for full observability in power systems. The weighted sum goal programming formulation incorporates the reliability of individual PMUs and finds a placement to resolve the conflicting objectives of minimum number of PMUs cost-wise and maximum level of system-wide reliability. This multi-objective problem is formulated as a nonlinear goal programming model in which weights are associated with the objectives. The model is solved for several weight scenarios for the IEEE 14, 30, 57 and 118 bus test systems....
Article Arabian Journal for Science and Engineering ; Volume 36, Issue 5 , 2011 , Pages 809-825 ; 13198025 (ISSN) ; Ehsan, M ; Sharif University of Technology
The characteristics of integrating distributed generation (DG) in a distribution network have changed. These electrical resources are used as an alternative energy source to the main grid. The technical and economical benefits of such units are achieved only when they are optimally sized and placed in the network. In this paper, a static mixed integer non-linear model for distributed generation planning is defined and solved using a modified NSGA method (Non-dominated Sorting Genetic Algorithm). Different DG technologies are considered and the objective functions for minimization are defined as the total active loss, investment and operational costs, and environmental pollution. The method...
Article International Journal of Information Technology and Decision Making ; Volume 14, Issue 4 , July , 2015 , Pages 769-803 ; 02196220 (ISSN) ; Farahani, R. Z ; De Brito, M. P ; Dullaert, W ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd 2015
Humanitarian logistics is regarded as a key area for improved disaster management efficiency and effectiveness. In this study, a multi-objective integrated logistic model is proposed to locate disaster relief centers while taking into account network costs and responsiveness. Because this location problem is NP-hard, we present a genetic approach to solve the proposed model
Multi-objective optimisation of McPherson strut suspension mechanism kinematics using Random Search Method, Article Indian Journal of Science and Technology ; July , 2015 , Volume 8, Issue 16 ; 09746846 (ISSN) ; Sina, N ; Eslami, A ; Sharif University of Technology
Indian Society for Education and Environment 2015
McPherson suspension mechanism is one of the widespread mounted mechanisms in front axle of Front Wheel Drive (FWD) vehicles with transverse engine. In this study the kinematics of McPherson suspension mechanism is optimised in order to achieve the desired kinematic behavior and improve vehicle stability. First, the mechanism was modeled in Mechanical Desktop software package and the model transferred to Working Model 3D software for kinematic analysis. Then results of kinematic simulation compared to design criteria and as target function is established, by choosing the optimal amount of optimisation variables the amount of cost function has been minimized. Because of simple...
Bi-objective reliability optimization of owitch-oode k-out-of-n series–parallel systems with active and cold standby components having failure rates dependent on the number of components, Article Arabian Journal for Science and Engineering ; Volume 42, Issue 12 , 2017 , Pages 5305-5320 ; 13198025 (ISSN) ; Akhavan Niaki, S. T ; Karimi, B ; Zaretalab, A ; Sharif University of Technology
This paper discusses a bi-objective reliability optimization of a switch-mode active and cold standby k-out-of-n series–parallel system in which a switch is installed to add a redundant component when one of the components fails. The system failure rate is not only dependent on the number of its working components, but reduces when more monitory resources are allocated. As the bi-objective optimization problem is shown to belong to the class of NP-hard problems, a multi-objective meta-heuristic algorithm, namely multi-objective evolutionary algorithm based on decomposition (MOEA/D) with a novel solution structure is developed to solve large-scale problems. Since there is no benchmark...