Search for: multi-objective-models
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    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) Pasandideh, S. H. R ; 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-objective market clearing model with an autonomous demand response scheme

    , Article Energies ; Volume 12, Issue 7 , 2019 ; 19961073 (ISSN) Hajibandeh, N ; Shafie Khah, M ; Badakhshan, S ; Aghaei, J ; Mariano, S. J. P. S ; Catalão, J. P. S ; Sharif University of Technology
    MDPI AG  2019
    Demand response (DR) is known as a key solution in modern power systems and electricity markets for mitigating wind power uncertainties. However, effective incorporation of DR into power system operation scheduling needs knowledge of the price–elastic demand curve that relies on several factors such as estimation of a customer’s elasticity as well as their participation level in DR programs. To overcome this challenge, this paper proposes a novel autonomous DR scheme without prediction of the price–elastic demand curve so that the DR providers apply their selected load profiles ranked in the high priority to the independent system operator (ISO). The energy and reserve markets clearing... 

    A web-based methodology for convergent product fuzzy networks using the Steiner tree

    , Article Journal of Industrial and Production Engineering ; Volume 30, Issue 7 , 2013 , Pages 415-432 ; 21681015 (ISSN) Hassanzadeh, R ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
    An important manufacturing technology spectrum is to consider rapid and sensitive assemblies through convergent product (CP) in digital environment. We integrate functions and sub-functions using a comprehensive mathematical optimization process. To form the CP, a web-based fuzzy network is considered in which a collection of base functions and sub-functions configure the nodes and each arc in the network is to be a link between two nodes. The aim is to find an optimal tree of functionalities in the network adding value to the product in the web environment. First, a purification process is performed in the product network to assign the links among bases and sub-functions. Then, fuzzy... 

    Controlled islanding for enhancing grid resilience against power system blackout

    , Article IEEE Transactions on Power Delivery ; Volume 36, Issue 4 , 2021 , Pages 2386-2396 ; 08858977 (ISSN) Kamali, S ; Amraee, T ; Fotuhi Firuzabad, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    This paper proposes a transient stability constrained controlled islanding (TSC-CI) approach against cascading events in power systems. Using the wide area measurements, the proposed islanding algorithm is implemented regarding the actual dynamic conditions of the resulted islands. Since the main concern, right after the execution of controlled network splitting, is the transient stability of synchronous machines, a transient energy function is utilized for proper network partitioning. The proposed transient stability criterion is expressed as a function of the transfer impedance between each pair of generators in the resulted islands. Transfer impedance between each pair of coherent... 

    Multi-objective design of risk-adjusted control chart in healthcare systems with economic and statistical considerations

    , Article Communications in Statistics: Simulation and Computation ; 2021 ; 03610918 (ISSN) Rafiei, N ; Asadzadeh, S ; Akhavan Niaki, S. T ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Using control charts to monitor healthcare systems has gained particular attention. In this paper, a risk-adjusted cumulative sum control chart is designed to monitor surgery outputs. Before undergoing surgery, the patients have some unique risk factors which influence the surgery outputs. Thus, risk-adjustment is carried out with the purpose of taking these risks into account using an accelerated failure time model. But the technical implementation of the chart requires determining the design parameters which should be selected in an optimal way putting the desired statistical and economic considerations into service. To this end, a multi-objective model, considering multiple assignable... 

    A multi-objective analysis for import quota policy making in a perishable fruit and vegetable supply chain: A system dynamics approach

    , Article Computers and Electronics in Agriculture ; Volume 93 , 2013 , Pages 37-45 ; 01681699 (ISSN) Teimoury, E ; Nedaei, H ; Ansari, S ; Sabbaghi, M ; Sharif University of Technology
    This study investigates a supply chain of perishable fruits and vegetables. A simulation model using system dynamics approach is proposed to study the behaviors and relationships within the supply chain and to determine the impact of the supply, demand and price interactions. The proposed model yields an insight into the overall agricultural system, taking into account the influence of import quota policies. The purpose of this study is to develop a multi-objective model identifying the best import quota policy for Tehran Municipality Organization of Fruits and Vegetables. The multiple objectives are considered to be price mean, price variation and markup. Key conclusions were reached on how... 

    Multi-objective optimization approach for green design of methanol plant based on CO2-efficeincy indicator

    , Article Journal of Cleaner Production ; Volume 103 , 2015 , Pages 640-650 ; 09596526 (ISSN) Taghdisian, H ; Pishvaie, M. R ; Farhadi, F ; Sharif University of Technology
    Elsevier Ltd  2015
    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... 

    Comparison of conventional and spherical reactor for the industrial auto-thermal reforming of methane to maximize synthesis gas and minimize CO2

    , Article International Journal of Hydrogen Energy ; Volume 42, Issue 31 , 2017 , Pages 19798-19809 ; 03603199 (ISSN) Shahhosseini, H. R ; Saeidi, S ; Najari, S ; Gallucci, F ; Sharif University of Technology
    Auto-thermal reforming (ATR), a combination of exothermic partial oxidation and endothermic steam reforming of methane, is an important process to produce syngas for petrochemical industries. In a commercial ATR unit, tubular fixed bed reactors are typically used. Pressure drop across the tube, high manufacturing costs, and low production capacity are some disadvantages of these reactors. The main propose of this study is to offer an optimized radial flow, spherical packed bed reactor as a promising alternative for overcoming the drawbacks of conventional tubular reactors. In the current research, a one dimensional pseudo-homogeneous model based on mass, energy, and momentum balances is... 

    A bi-objective aggregate production planning problem with learning effect and machine deterioration: modeling and solution

    , Article Computers and Operations Research ; Volume 91 , March , 2018 , Pages 21-36 ; 03050548 (ISSN) Mehdizadeh, E ; Akhavan Niaki, S. T ; Hemati, M ; Sharif University of Technology
    Elsevier Ltd  2018
    The learning effects of the workers and machine deterioration in an aggregate production planning (APP) problem have not been taken into account in the literature yet. These factors affect the performance of any real-world production system and require attention. In this paper, a bi-objective optimization model is developed for an APP problem with labor learning effect and machine deterioration. The first objective of this model maximizes the profit by improving learning and reducing the failure cost of the system. The second objective function minimizes the costs associated with repairs and deterioration, which depend on the failure rate of the machines in the production periods. The aim of... 

    Optimal network configuration considering network losses and service reliability

    , Article IEEE Proceedings 2017 Smart Grid Conference, SGC 2017 ; Volume 2018-January , 2018 , Pages 1-6 ; 9781538642795 (ISBN) Gharebaghi, S ; Izadi, M ; Safdarian, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Distribution networks are designed in loop structure, while they are operated as radial networks. In this regard, the location of normally open (NO) switches is usually determined by either minimizing real power losses or maximizing the reliability level. However, considering both losses and reliability in the decision making procedure may lead to a better solution. To do so, this paper proposes a mathematical model to find the optimal configuration of NO switches such that losses and reliability are optimized. The multi-objective model is scrutinized via weighted sum approach to achieve a single-objective model. The model is formulated in mixed integer quadratically constrained programming... 

    Co-reconfiguration of product family and supply chain using leader–follower Stackelberg game theory: Bi-level multi-objective optimization

    , Article Applied Soft Computing Journal ; Volume 91 , 2020 Pakseresht, M ; Mahdavi, I ; Shirazi, B ; Mahdavi Amiri, N ; Sharif University of Technology
    Elsevier Ltd  2020
    This article deals with product Family: a group of products with similar modules produced based on assembling to order (ATO) approach to cover diverse customer needs. The demand level and the customer requirements of these products are dynamically changing, which necessitate a novel model for co-reconfiguration of the product family (PF) and the supply chain (SC). Therefore, this article aims to apply Leader–follower Stackelberg Game Theory in order to present a co-reconfiguration of PF and SC based on three objectives: maximizing the total profit, maximizing customer utility and minimizing the supply chain cost in a bi-level structure. Maximizing the total profit and maximizing customer... 

    Estimation of origin–destination matrices using link counts and partial path data

    , Article Transportation ; Volume 47, Issue 6 , 2020 , Pages 2923-2950 Rostami Nasab, M ; Shafahi, Y ; Sharif University of Technology
    Springer  2020
    After several decades of work by several talented researchers, estimation of the origin–destination matrix using traffic data has remained very challenging. This paper presents a set of innovative methods for estimation of the origin–destination matrix of large-scale networks, using vehicle counts on links, partial path data obtained from an automated vehicle identification system, and combinations of both data. These innovative methods are used to solve three origin–destination matrix estimation models. The first model is an extension of Spiess’s model which uses vehicle count data while the second model is an extension of Jamali’s model and it uses partial path data. The third model is a... 

    A heuristic trade off model for integration of distributed generations in deregulated power systems considering technical, economical and environmental issues

    , Article 2008 IEEE 2nd International Power and Energy Conference, PECon 2008, Johor Baharu, 1 December 2008 through 3 December 2008 ; 2008 , Pages 1275-1279 ; 9781424424054 (ISBN) Hekmati, A ; Nasiri, R ; Bagheri, M ; Tehrani, A. A ; Sharif University of Technology
    With the introduction of restructuring concepts to traditional power systems, a great deal of attention is given to the utilization of distributed generation. Since the integration of DG units has been known as an alternative for main grid as a resource for energy supply, the determination of optimal sizing and sitting is an important issue in the planning procedure of DG. This work presents a comprehensive multi-objective model for integration of distributed generations into a distribution network, regarding various technical, economical and environmental issues such as reduction of carbon dioxide emissions and investment & running costs while the bus voltages shall be kept within...