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Application of machine-learning models to estimate regional input coefficients and multipliers
, Article Spatial Economic Analysis ; Volume 17, Issue 2 , 2022 , Pages 178-205 ; 17421772 (ISSN) ; Kashani, H ; Sharif University of Technology
Routledge
2022
Abstract
Due to the unavailability of accurate data and the limitations of the existing methods, reliable input–output tables (IOTs) may not be available for all the regions in a country. This study proposes a novel approach to estimate the regional input coefficients. It harnesses the capabilities of machine-learning (ML) algorithms to estimate the regional input coefficients of one region based on the IOTs of multiple other regions for which reliable data are available. The application of three ML algorithms is investigated using data from Japan. The results highlight the superior performance of the ML models compared with location quotient models. © 2021 Regional Studies Association
A Heuristic Method for the Integrated Multi-Depots Continuous Location-Routing and Inventory Problem
, M.Sc. Thesis Sharif University of Technology ; Eshghi, Kourosh (Supervisor)
Abstract
In this study a mathematical model has been presented for multi depots, continuous location-routing problem with inventory restrictions. In this problem, a three-echelon supply chain was assumed and a factory which is producing one product and with unlimited capacity is on the first echelon of supply chain. In the second echelon of supply chain, several distribution centers distribute products. In the third echelon, there is a set of customers who are scattered in different geographical locations. Location of customers is pre-specified, but distribution centers should be located. In this problem, location of distribution centers will be determined in a continuous space. As the leader of this...
Hub location problem considering an elastic demand
, Article CIE 2014 - 44th International Conference on Computers and Industrial Engineering and IMSS 2014 - 9th International Symposium on Intelligent Manufacturing and Service Systems, Joint International Symposium on "The Social Impacts of Developments in Information, Manufacturing and Service Systems" - Proceedings ; 2014 , pp. 581-588 ; Akbari Jokar, M. R ; Sharif University of Technology
Abstract
In most hub location problem in the literature, the demand is independent of the market share. However, especially about the services and products which are not essential, this assumption does not mirror the reality. Considering the elastic demand increases the complexity and solution of the problem. The elasticity of demand depends on the utility of available hub. For simplicity, we assume that the utility of hub nodes are additive. Utility of the nodes is based on the attraction of the facility on that node and also the decay function of distance. In this paper we propose a new model for hub location problem in an airline industry with elastic demand. In this problem, passengers use hubs...
SAR processing to localize LPI radars
, Article 2014 International Radar Conference ; 2014 ; ISBN: 9781479941957 ; Norouzi, Y ; Nayebi, M. M ; Sharif University of Technology
Abstract
In this paper a new passive imaging method is introduced that is mainly suitable for Geo-locating LPI radars. The method uses two Electronic Support (ES) receivers located on a fast moving platform (e.g. an airplane or a satellite). The proposed method has a high processing gain which makes it absolutely suitable against very weak LPI signals. It is also capable in radar location finding against complex radars and complicated electromagnetic environment
A soft-computing Pareto-based meta-heuristic algorithm for a multi-objective multi-server facility location problem
, Article Applied Soft Computing Journal ; Volume 13, Issue 4 , 2013 , Pages 1728-1740 ; 15684946 (ISSN) ; Hajipour, V ; Niaki, S. T. A ; Sharif University of Technology
2013
Abstract
In this paper, a novel multi-objective location model within multi-server queuing framework is proposed, in which facilities behave as M/M/m queues. In the developed model of the problem, the constraints of selecting the nearest-facility along with the service level restriction are considered to bring the model closer to reality. Three objective functions are also considered including minimizing (I) sum of the aggregate travel and waiting times, (II) maximum idle time of all facilities, and (III) the budget required to cover the costs of establishing the selected facilities plus server staffing costs. Since the developed model of the problem is of an NP-hard type and inexact solutions are...
Genetic application in a facility location problem with random demand within queuing framework
, Article Journal of Intelligent Manufacturing ; Volume 23, Issue 3 , 2012 , Pages 651-659 ; 09565515 (ISSN) ; Niaki, S. T. A ; Sharif University of Technology
2012
Abstract
In many service and industrial applications of the facility location problem, the number of required facilities along with allocation of the customers to the facilities are the two major questions that need to be answered. In this paper, a facility location problem with stochastic customer demand and immobile servers is studied. Two objectives considered in this problem are: (1) minimizing the average customer waiting time and (2) minimizing the average facility idletime percentage. We formulate this problem using queuing theory and solve the model by a genetic algorithm within the desirability function framework. Several examples are presented to demonstrate the applications of the proposed...
Optimizing capacity, pricing and location decisions on a congested network with balking
, Article Mathematical Methods of Operations Research ; Volume 74, Issue 2 , October , 2011 , Pages 233-255 ; 14322994 (ISSN) ; Babri, S ; Berman, O ; Shavandi, H ; Sharif University of Technology
2011
Abstract
In this paper, we consider the problem of making simultaneous decisions on the location, service rate (capacity) and the price of providing service for facilities on a network. We assume that the demand for service from each node of the network follows a Poisson process. The demand is assumed to depend on both price and distance. All facilities are assumed to charge the same price and customers wishing to obtain service choose a facility according to a Multinomial Logit function. Upon arrival to a facility, customers may join the system after observing the number of people in the queue. Service time at each facility is assumed to be exponentially distributed. We first present several...
A new algorithm for fault location on transmission lines by optimal PMU placement
, Article International Transactions on Electrical Energy Systems ; Volume 25, Issue 10 , 2015 , Pages 2071-2086 ; 20507038 (ISSN) ; Salehi Dobakhshari, A ; Ranjbar, A. M ; Tayebi, A ; Sharif University of Technology
John Wiley and Sons Ltd
2015
Abstract
In this paper, the problem of placing a minimum number of phasor measurement units (PMUs) in a transmission system is considered so that faults on all lines of the network can be diagnosed and located irrespective of their locations. For this purpose, a PMU placement algorithm is applied to calculate the required data for impedance-based fault location of any fault line in the network, achieving the full potential of the circuit laws throughout the system. Another algorithm is then proposed to compute the voltage and current values of the fault line for fault-location purposes. Moreover, as many networks are already equipped with PMUs, the proposed algorithm makes it possible to locate...
2PLoc: Preserving privacy in location-based services
, Article Proceedings - SocialCom 2010: 2nd IEEE International Conference on Social Computing, PASSAT 2010: 2nd IEEE International Conference on Privacy, Security, Risk and Trust, 20 August 2010 through 22 August 2010 ; August , 2010 , Pages 707-712 ; 9780769542119 (ISBN) ; Kharrazi, M ; Jalili, R ; Sharif University of Technology
2010
Abstract
Location-based services are becoming popular for mobile users. The mobile users' location plays a key role to provide the service from one side, but it can be considered as a dimension of their privacy and so necessary to keep it anonymous to the other parties. Since one important issue is to achieve an accurate service, it is important to use the mobile's accurate location. Using the location accurately raises some concerns on behalf of the user's privacy. One solution for meeting this requirement is using tickets by the means of a third party. The tickets should have some properties for not letting a mobile user to cheat and use the ticket more than one time. This paper proposes a protocol...
A hybrid imperialist competitive-simulated annealing algorithm for a multisource multi-product location-routing-inventory problem
, Article Computers and Industrial Engineering ; Volume 101 , 2016 , Pages 116-127 ; 03608352 (ISSN) ; Akbari jokar, M. R ; Sharif University of Technology
Elsevier Ltd
Abstract
This article studies a multi-product and multi-period location-routing-inventory problem in which location-allocation, inventory and routing decisions are to be taken in a three-level supply chain including suppliers, depots and customers. Products are distributed from depots to customers by a homogeneous fleet of vehicles. Backlogging is allowable on condition that the backlog quantity of each customer does not exceed a predefined fraction of his demand. A mixed-integer programming formulation is presented to describe the problem then a new hybrid heuristic algorithm based on the simulated annealing and imperialist competitive algorithm is designed to solve the model. Comprehensive...
Hybridizations of genetic algorithms and neighborhood search metaheuristics for fuzzy bus terminal location problems
, Article Applied Soft Computing Journal ; Volume 46 , 2016 , Pages 220-229 ; 15684946 (ISSN) ; Ghanbari, R ; Mahdavi Amiri, N ; Sharif University of Technology
Elsevier Ltd
Abstract
We propose modified hybridizations of genetic algorithms with some neighborhood search based metaheuristics. In our hybrid algorithms, we consider gradually increasing probability for the application of the neighborhood search procedure on the best individuals as the number of iterations of the genetic algorithm increases. We implement the proposed hybrid algorithms and compare their performance with two other recently proposed hybrid algorithms which, in contrast, use the neighborhood search procedure on all the individuals of the population, two hybrid algorithms applying simulated annealing on the best individual in the papulation in every iteration and three non-hybrid metaheuristic...
A location privacy-preserving method for spectrum sharing in database-driven cognitive radio networks
, Article Wireless Personal Communications ; Volume 95, Issue 4 , 2017 , Pages 3687-3711 ; 09296212 (ISSN) ; Ahmadian Attari, M ; Jannati, H ; Aref, M. R ; Sharif University of Technology
Springer New York LLC
2017
Abstract
The great attention to cognitive radio networks (CRNs) in recent years, as a revolutionary communication paradigm that aims to solve the problem of spectrum scarcity, prompts serious investigation on security issues of these networks. One important security concern in CRNs is the preservation of users location privacy, which is under the shadow of threat, especially in database-driven CRNs. To this end, in this paper, we propose a Location Privacy Preserving Database-Driven Spectrum-Sharing (L-PDS 2) protocol for sharing the spectrum between PUs and SUs in a database-driven CRN, while protecting location privacy of both primary and secondary users, simultaneously. We also present two...
A risk-averse location-protection problem under intentional facility disruptions: a modified hybrid decomposition algorithm
, Article Transportation Research Part E: Logistics and Transportation Review ; Volume 114 , June , 2018 , Pages 196-219 ; 13665545 (ISSN) ; Seifbarghy, M ; Akhavan Niaki, S. T ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The rising disruptions of interdictors force supply chains’ designers to embody the protection decisions when locating the facilities. In the presence of variability in the intensity of disruptions, a risk measure is incorporated into the decision-making. The designer-interdictor bi-level problem, therefore, optimizes the joint location and protection decisions with respect to the conditional value-at-risk. This configuration has been absent from the literature. An accelerated modified Benders decomposition algorithm is developed and enhanced by being hybridized with a sample average approximation-based genetic algorithm. We examine how this new configuration influences the optimal solutions...
Deployment of fault indicator in distribution networks: a MIP-based approach
, Article IEEE Transactions on Smart Grid ; Volume 9, Issue 3 , May , 2018 , Pages 2259-2267 ; 19493053 (ISSN) ; Fotuhi Firuzabad, M ; Safdarian, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Fault indicator (FI) plays a crucial rule in enhancing service reliability in distribution systems. This device brings substantial benefits for fault management procedure by speeding up fault location procedure. This paper intends to develop a new optimization model to optimally deploy FI in distribution systems. The proposed model aims to consider a tradeoff between the total customer interruption cost and FI relevant costs, including capital investment, installation, and maintenance costs. As the main contribution of this paper, the problem is formulated in mixed integer programing, which guarantees global optimum solution achieved in an effective runtime. Moreover, the model takes...
Vehicle identification sensors location problem for large networks
, Article Journal of Intelligent Transportation Systems: Technology, Planning, and Operations ; Volume 23, Issue 4 , 2019 , Pages 389-402 ; 15472450 (ISSN) ; Shafahi, Y ; Sharif University of Technology
Taylor and Francis Inc
2019
Abstract
Finding the optimal location for sensors is a key problem in flow estimation. There are several location models that have been developed recently for vehicle identification (ID) sensors. However, these location models cannot be applied to large networks because there are many constraints and integer variables. Based on a property of the location problem for vehicle ID sensors, given the initial vehicle ID sensors that are pre-installed and fixed on the network, this article presents a solution that greatly reduces the size of this location problem. An applied example demonstrates that when 8% of the arcs from a real network that are randomly selected have a vehicle ID sensor, the reductions...
Facility location optimization via multi-agent robotic systems
, Article 2008 IEEE International Conference on Networking, Sensing and Control, ICNSC, Sanya, 6 April 2008 through 8 April 2008 ; 2008 , Pages 287-292 ; 9781424416851 (ISBN) ; Sayyaadi, H ; Sharif University of Technology
2008
Abstract
A facility location problem deals with locating the best place for a group of facilities, among distinct demand points, minimizing a certain locational optimization function. In this paper, distributed, asynchronous, and scalable algorithms are presented for solving a facility location problem known as continuous n-median problem (generalized Fermat-Weber problem) via multi-agent robotic systems. The algorithms are discussed both in continuous and discrete time domain, and their validity is proved. It is also shown that the solution of this facility location problem is the set of points that are the geometric medians of their corresponding Voronoi cells
Competitive facility location problem with foresight considering discrete-nature attractiveness for facilities: Model and solution
, Article Computers and Operations Research ; Volume 146 , 2022 ; 03050548 (ISSN) ; Tavakkoli Moghaddam, R ; Fazeli, E ; Arefkhani, H ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This paper addresses a bi-level mixed-integer nonlinear programming (MINLP) model for the competitive facility location problem in a closed-loop supply chain (CLSC), in which a firm (i.e., leader) aims at entering a market by locating new distribution and collection facilities, where a competitor (i.e., follower) already exists. The goal is to find the location and attractiveness of each facility going to be established by the leader who seeks to maximize its profit while also taking the follower's response into account. The attractiveness of each facility is a function of integer variables related to the facility's characteristics. Customer behavior is considered to be probabilistic based...
Optimal Relay Location in Wireless Networks
, M.Sc. Thesis Sharif University of Technology ; Golestani, Jamaloddin (Supervisor) ; Nasiri-Kenari, Masoumeh (Co-Advisor)
Abstract
According to the wide range of applications and numerous implementations, wireless networks are considered as a prominent means of providing data services, and have attracted the attention of many researches in recent years. Performance enhancement of these networks can be very beneficial to industry and wireless data service providers. Manipulation of relays, have been always considered as a proper means for improvement of network performance measures throughput and outage probability.In order to design relay networks efficiently, one should address two following problems: 1- determining transmission policy, and 2- relay location. In this research work, having in mind the optimality of...
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hassan (Supervisor)
Abstract
In this research, the location-inventory problem is developed in order to design a distribution center considering customers behavior. We consider two groups of customers who have different behavior on purchase. The customers may order the product via internet and receive it at their location or go to the nearest store and buy the product at the store center. We model the problem as a multi-objective programming model. The objectives are maximizing the profit as well as maximizing the market share. The model locates the distribution centers (DC) and allocates the customers to DCs. Two heuristic algorithms developed to solve the model: non- dominated Sorting Genetic Algorithm (NSGA-II) and...
A Location-Routing-Inventory Problem with Cross-Docking and Split Delivery
, M.Sc. Thesis Sharif University of Technology ; Akbari Jokar, Mohammad Reza (Supervisor)
Abstract
This paper studies a multi-product, multi-period location- routing- inventory problem in a three-level supply chain including suppliers, cross-docks and customers. Each cross-dock could be supplied by more than one supplier and each customer could be supplied by more than one cross-dock. In the first phase we find the best locations for the cross-dock and allocate them to customers and suppliers by considering inventory costs. . Then, in the second phase Products are distributed from cross-docks towards customers using Heterogeneous vehicles. In this article the option for split delivery is enabled and furthermore, backlogging is allowable for each customer. The model presented in this...