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Assessment of a parallel evolutionary optimization approach for efficient management of coastal aquifers
, Article Environmental Modelling and Software ; Volume 74 , December , 2015 , Pages 21-38 ; 13648152 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This study presents a parallel evolutionary optimization approach to determine optimal management strategies of large-scale coastal groundwater problems. The population loops of evolutionary algorithms (EA) are parallelized using shared memory parallelism to address the high computational demands of such applications. This methodology is applied to solve the management problems in an aquifer system in Kish Island, Iran using a three-dimensional density-dependent groundwater numerical model. EAs of continuous ant colony optimization (CACO), particle swarm optimization, and genetic algorithm are utilized to solve the optimization problems. By implementing the parallelization strategy, a...
Path-differentiated pricing in congestion mitigation
, Article Transportation Research Part B: Methodological ; Volume 80 , October , 2015 , Pages 202-219 ; 01912615 (ISSN) ; Aashtiani, H. Z ; Lawphongpanich, S ; Yin, Y ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Instead of charging tolls on individual links, this paper considers doing the same on paths. Path and link tolls are "valid" if they encourage motorists to use routes that collectively lead to a target distribution, e.g., one that minimizes travel delay. Because the numbers of valid link and path tolls are typically infinite, an objective in pricing tolls is to find a set of valid tolls that yields the least revenue to lessen the financial burden on motorists.Path tolls are generally more flexible than link tolls and this paper shows that this flexibility can substantially reduce the financial burden on motorists. Additionally, valid path tolls yielding the least revenue possess...
An efficient algorithm for the multi-state two separate minimal paths reliability problem with budget constraint
, Article Reliability Engineering and System Safety ; Volume 142 , October , 2015 , Pages 472-481 ; 09518320 (ISSN) ; Mahdavi Amiri, N ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Abstract Several researchers have worked on transmitting a given amount of flow through a network flow within fastest possible time, allowing flow to be transmitted through one or more paths. Extending this problem to the system reliability problem, the quickest path reliability problem has been introduced. The problem evaluates the probability of transmitting some given amount of flow from a source node to a sink node through a single minimal path in a stochastic-flow network within some specified units of time. Later, the problem has been extended to allow flow to be transmitted through two or more separate minimal paths (SMPs). Here, we consider the problem of sending flow through two...
A new approach to multi-objective optimisation method in PEM fuel cell
, Article International Journal of Sustainable Energy ; Volume 34, Issue 5 , Jul , 2015 , Pages 283-297 ; 14786451 (ISSN) ; Hoseini, A ; Roshandel, R ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
This paper presents an optimisation model for polymer electrolyte membrane fuel cell system based on simultaneous power maximisation and cost minimisation. The results show that, by employing appropriate relation between the objectives, the innovative design could be proposed. Genetic algorithm is applied to solve the optimisation problem. Power maximisation results reveal that at maximum amount of power (1.95 kW), unit cost of energy is $0.64. In contrast, minimisation of cost decreases unit cost of energy to $0.33. In this condition, output power is reduced approximately to 0.93 kW. To consider both optimisation problems concurrently, weighting method and Pareto set are employed. Our...
Developing a two-stage procedure for Estimating Origin-Destination matrix based on routes and traffic volumes
, Article IEOM 2015 - 5th International Conference on Industrial Engineering and Operations Management, Proceeding, 3 March 2015 through 5 March 2015 ; 2015 ; 9781479960651 (ISBN) ; Mahmoudabadi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Estimating Origin-Destination matrix, named O-D matrix or ODM, is an important issue in transportation planning. Due to need to survey movements on the network, estimating ODM is usually considered as a high-cost measure in transportation planning. In this research work, a two-stage procedure, including solving routing problem and minimizing the difference between observed and estimated traffic volumes on the network, has been developed to estimate the O-D matrix elements. At the first stage, routing problem is solved to determine paths while in the second stage an absolute error function has been defined to determine the number of trips from each origin to destination pairs. The procedure...
An outer approximation method for an integration of supply chain network designing and assembly line balancing under uncertainty
, Article Computers and Industrial Engineering ; Volume 83 , 2015 , Pages 297-306 ; 03608352 (ISSN) ; Salehi, N ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this paper a new model is proposed for the integrated problem of supply chain network designing and assembly line balancing under demand uncertainty. In this problem there are three types of entities: manufacturers, assemblers and customers. Manufacturers provide assemblers with components and assemblers use these components to produce the final products and satisfy the demand of the customers. This problem involves determining the location of manufacturers and assemblers in the network, balancing the assembly lines, and transportation of materials and products throughout the network. A mixed integer nonlinear programming formulation based on two stage stochastic programming method is...
Optimization of a multiproduct economic production quantity problem with stochastic constraints using sequential quadratic programming
, Article Knowledge-Based Systems ; Volume 84 , 2015 , Pages 98-107 ; 09507051 (ISSN) ; Akhavan Niaki, S. T ; Gharaei, A ; Sharif University of Technology
Elsevier
2015
Abstract
In this paper, a multiproduct single vendor-single buyer supply chain problem is investigated based on the economic production quantity model developed for the buyer to minimize the inventory cost. The model to be more applicable for real-world supply chain problems contains five stochastic constraints including backordering cost, space, ordering, procurement, and available budget. The objective is to find the optimal order quantities of the products such that the total inventory cost is minimized while the constraints are satisfied. The recently-developed sequential quadratic programming (SQP), as one of the best optimization methods available in the literature, is used to solve the...
Two parameter tuned multi-objective evolutionary algorithms for a bi-objective vendor managed inventory model with trapezoidal fuzzy demand
, Article Applied Soft Computing Journal ; Volume 30 , May , 2015 , Pages 567-576 ; 15684946 (ISSN) ; Akhavan Niaki, S. T ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This paper presents a bi-objective vendor managed inventory (BOVMI) model for a supply chain problem with a single vendor and multiple retailers, in which the demand is fuzzy and the vendor manages the retailers' inventory in a central warehouse. The vendor confronts two constraints: number of orders and available budget. In this model, the fuzzy demand is formulated using trapezoidal fuzzy number (TrFN) where the centroid defuzzification method is employed to defuzzify fuzzy output functions. Minimizing both the total inventory cost and the warehouse space are the two objectives of the model. Since the proposed model is formulated into a bi-objective integer nonlinear programming (INLP)...
Bi-objective optimization of a multi-product multi-period three-echelon supply chain problem under uncertain environments: NSGA-II and NRGA
, Article Information Sciences ; Volume 292 , January , 2015 , Pages 57-74 ; 00200255 (ISSN) ; Akhavan Niaki, S. T ; Asadi, K ; Sharif University of Technology
Elsevier Inc
2015
Abstract
Bi-objective optimization of a multi-product multi-period three-echelon supply-chain-network problem is aimed in this paper. The network consists of manufacturing plants, distribution centers (DCs), and customer nodes. To bring the problem closer to reality, the majority of the parameters in this network including fixed and variable costs, customer demand, available production time, set-up and production times, all are considered stochastic. The goal is to determine the quantities of the products produced by the manufacturing plants in different periods, the number and locations of the warehouses, the quantities of products transported between the supply chain entities, the inventory of...
Swarm intelligent compressive routing in wireless sensor networks
, Article Computational Intelligence ; Volume 31, Issue 3 , 2015 , Pages 513-531 ; 08247935 (ISSN) ; Sarrafzadeh, A ; Mehrjoo, M ; Sharif University of Technology
Blackwell Publishing Inc
2015
Abstract
This article proposes a novel algorithm to improve the lifetime of a wireless sensor network. This algorithm employs swarm intelligence algorithms in conjunction with compressive sensing theory to build up the routing trees and to decrease the communication rate. The main contribution of this article is to extend swarm intelligence algorithms to build a routing tree in such a way that it can be utilized to maximize efficiency, thereby rectifying the delay problem of compressive sensing theory and improving the network lifetime. In addition, our approach offers accurate data recovery from small amounts of compressed data. Simulation results show that our approach can effectively extend the...
Comparison between different multi-objective approaches to distribution network planning
, Article IET Conference Publications ; Volume 2013, Issue 615 CP , 2013 ; 9781849197328 (ISBN) ; Eini, B. J ; Mirvazand, M ; Safari, M ; Sharif University of Technology
2013
Abstract
Distribution companies try to meet different goals such as increasing profitability, reducing investment and improving reliability indices. Therefore, distribution network planning has converted into complex multi-objective optimization problems. Mathematicians and operation research experts have developed many methods which can be used for solving these problems. Despite all efforts to develop applicable approaches for these problems, there is still no general consensus on project selection policy. Evaluating the strengths and weaknesses of each network optimization strategy selection in pragmatic manner is the objective of current research. In this paper, many methods used in network...
Dictionary learning for sparse representation: A novel approach
, Article IEEE Signal Processing Letters ; Volume 20, Issue 12 , 2013 , Pages 1195-1198 ; 10709908 (ISSN) ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
2013
Abstract
A dictionary learning problem is a matrix factorization in which the goal is to factorize a training data matrix, Y, as the product of a dictionary, D, and a sparse coefficient matrix, X, as follows, Y ≈ DX. Current dictionary learning algorithms minimize the representation error subject to a constraint on D (usually having unit column-norms) and sparseness of X. The resulting problem is not convex with respect to the pair (D, X). In this letter, we derive a first order series expansion formula for the factorization, DX. The resulting objective function is jointly convex with respect to D and X. We simply solve the resulting problem using alternating minimization and apply some of the...
Multi-period lot sizing and job shop scheduling with compressible process times for multilevel product structures
, Article International Journal of Production Research ; Volume 51, Issue 20 , 2013 , Pages 6229-6246 ; 00207543 (ISSN) ; Seyedhoseini, S. M ; Modarres, M ; Heidari, M ; Sharif University of Technology
2013
Abstract
This paper presents mathematical modelling of joint lot sizing and scheduling problem in job shop environment under a set of working conditions. The main feature of the problem is to deal with flexible machines able to change their working speeds, known as process compressibility. Furthermore, produced items should be assembled together to make final products. In other words, the products have a multilevel structure, shown with bill of materials. As the problem is proved to be strongly NP-hard, it is solved by a memetic algorithm here. Computational experiences on the data of Mega Motor company are reported. Also, further experiences on random test data confirm the performance of the...
Makespan minimisation in flexible flowshop sequence-dependent group scheduling problem
, Article International Journal of Production Research ; Volume 51, Issue 20 , 2013 , Pages 6182-6193 ; 00207543 (ISSN) ; Salmasi, N ; Sharif University of Technology
2013
Abstract
In this research, the flexible flowshop sequence-dependent group scheduling problem with minimisation of makespan as the criterion (FFm|fmls, shgi|Cmax) is investigated. A mixed integer linear mathematical model for the research problem is developed. Since the research problem is shown to be NP-hard, a meta-heuristic algorithm based on memetic algorithm (MA) is developed to efficiently solve the problem. Also, a lower bounding technique based on the developed mathematical model is proposed to evaluate the quality of the proposed MA. The performance of the proposed MA is compared with the existing algorithm in the literature, i.e. tabu search (TS), by solving the available test problems in...
Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators
, Article Robotica ; Volume 31, Issue 7 , 2013 , Pages 1073-1084 ; 02635747 (ISSN) ; Zohoor, H ; Korayem, M. H ; Sharif University of Technology
2013
Abstract
Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators is a new practical problem in robotics. The problem concerns with determining the type of each manipulator module from among several specific types, so that the manipulator could reach several specified target frames with the lowest error. This paper suggests using a breadth-first search method and a workspace mean frame to solve this problem. To reduce errors, two heuristic ideas are proposed: two-by-two searching method and iteration. The effectiveness of the proposed method is verified through several numerical problems
Optimizing a multi-vendor multi-retailer vendor managed inventory problem: Two tuned meta-heuristic algorithms
, Article Knowledge Based Systems ; Volume 50 , September , 2013 , Pages 159-170 ; 09507051 (ISSN) ; Mousavi, S. M ; Niaki, S. T. A ; Sadeghi, S ; Sharif University of Technology
2013
Abstract
The vendor-managed inventory (VMI) is a common policy in supply chain management (SCM) to reduce bullwhip effects. Although different applications of VMI have been proposed in the literature, the multi-vendor multi-retailer single-warehouse (MV-MR-SW) case has not been investigated yet. This paper develops a constrained MV-MR-SW supply chain, in which both the space and the annual number of orders of the central warehouse are limited. The goal is to find the order quantities along with the number of shipments received by retailers and vendors such that the total inventory cost of the chain is minimized. Since the problem is formulated into an integer nonlinear programming model, the...
Beyond the cut-set bound: Uncertainty computations in network coding with correlated sources
, Article IEEE Transactions on Information Theory ; Volume 59, Issue 9 , 2013 , Pages 5708-5722 ; 00189448 (ISSN) ; Yang, S ; Jaggi, S ; Sharif University of Technology
2013
Abstract
Cut-set bounds are not, in general, tight for all classes of network communication problems. In this paper, we introduce a new technique for proving converses for the problem of transmission of correlated sources in networks, which results in bounds that are tighter than the corresponding cut-set bounds. We also define the concept of 'uncertainty region' which might be of independent interest. We provide a full characterization of this region for the case of two correlated random variables. The bounding technique works as follows: on one hand, we show that if the communication problem is solvable, the uncertainty of certain random variables in the network with respect to imaginary parties...
Joint single vendor-single buyer supply chain problem with stochastic demand and fuzzy lead-time
, Article Knowledge-Based Systems ; Volume 48 , 2013 , Pages 1-9 ; 09507051 (ISSN) ; Niaki, S. T .A ; Wee, H. M ; Sharif University of Technology
2013
Abstract
This study solves a chance-constraint supply chain problem with stochastic demand which follows a uniform distribution. Fuzzy delay times (moving, waiting and setup time) are assumed to be lot size dependent and shortage is partially backordered. The buyer is responsible for the costs incurred in ordering, holding, shortage and transportation, while the vendor is responsible for setup and holding costs. The service rate of each product has a chance constraint and the buyer has a budget constraint. Our objective is to determine the re-order point and the order quantity of the products such that the total cost is minimized. Since the problem is uncertain integer-nonlinear, two hybrid...
Composite power system adequacy assessment based on postoptimal analysis
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 21, Issue 1 , 2013 , Pages 90-106 ; 13000632 (ISSN) ; Fotuhi Firuzabad, M ; Aminifar, F ; Sharif University of Technology
2013
Abstract
The modeling and evaluation of enormous numbers of contingencies are the most challenging impediments associated with composite power system adequacy assessment, particularly for large-scale power systems. Optimal power flow (OPF) solution, as a widely common approach, is normally employed to model and analyze each individual contingency as an independent problem. However, mathematical representations associated with diverse states are slightly different in one or a few generating units, line outages, or trivial load variations. This inherent attribute brings a promising idea to speed up the contingency evaluation procedure. In this paper, postoptimal analysis (POA), as a well-recognized...
Capacitated location allocation problem with stochastic location and fuzzy demand: A hybrid algorithm
, Article Applied Mathematical Modelling ; Volume 37, Issue 7 , 2013 , Pages 5109-5119 ; 0307904X (ISSN) ; Akhavan Niaki, S. T ; Sharif University of Technology
2013
Abstract
In this article, a capacitated location allocation problem is considered in which the demands and the locations of the customers are uncertain. The demands are assumed fuzzy, the locations follow a normal probability distribution, and the distances between the locations and the customers are taken Euclidean and squared Euclidean. The fuzzy expected cost programming, the fuzzy β-cost minimization model, and the credibility maximization model are three types of fuzzy programming that are developed to model the problem. Moreover, two closed-form Euclidean and squared Euclidean expressions are used to evaluate the expected distance between customers and facilities. In order to solve the problem...