Search for: costs
Total 1460 records
Article Applied Mathematics and Computation ; Volume 217, Issue 17 , 2011 , Pages 7051-7052 ; 00963003 (ISSN) ; Alimomeni, M ; Sharif University of Technology
We reduce the problem of minimum interval cost flow problem (MICFP) introduced by Hashemi et al. (2006) to the well-known minimum cost flow problem (MCFP)
Article Technological Forecasting and Social Change ; Volume 138 , 2019 , Pages 243-253 ; 00401625 (ISSN) ; Rahmani, R ; Fateh rad, M ; Sharif University of Technology
Elsevier Inc 2019
Large technology-intensive enterprises and companies face a constant challenge: How can a set of selected high-tech projects get done in a manner that would minimize the total cost across all projects? In majority of cases, projects are assumed independent, leading to a separate cost evaluation. This assumption often does not hold for real-world project portfolios, frequently sharing overlapping technologies. In this paper, we show how the order of the execution of the projects can directly affect the total cost of the portfolio, due to shared dependencies. Modeling the problems in this area can be achieved by combining two main fields: graph theory and technology mining. A novel method is...
Article Australian Journal of Electrical and Electronics Engineering ; Volume 7, Issue 3 , 2010 , Pages 211-223 ; 1448837X (ISSN) ; Vakilian, M ; Blackburn, T. R ; Sharif University of Technology
The first step in the accepted methods of overhead transmission line insulation coordination is to specify a reliability criterion, and then based on this constraint the most economic insulation design is sought. While the objective of an optimal insulation design method is to find an insulation design that minimises the total cost (the sum of the installation cost, operational cost and cost of failure), each of the cost components can be determined on a per-year basis taking into account the equipment's lifetimes. In this paper, through application of ATP software and realising the total cost of different transmission line designs, a set of alternative insulation designs using various surge...
From loss allocation to loss cost allocation: a comparative study of different loss cost allocation methods, Article International Transactions on Electrical Energy Systems ; Volume 23, Issue 4 , 2013 , Pages 586-600 ; 20507038 (ISSN) ; Ehsan, M ; Fotuhi Firuzabad, M ; Parvania, M ; Sharif University of Technology
As a high proportion of the total generated electricity energy and the power system costs is due to the power losses in lines, allocating the loss and associated cost to the system loads and generating units is a substantial issue in deregulated power systems. The procedure to accomplish this cost allocation is designated as 'loss cost allocation' (LCA). So far, a number of LCA methods have been proposed for transmission networks. A few papers have compared different loss allocation methods, which are the methods which calculate the loss (and not necessarily the loss cost) allocated to the loads and generating units. However, this paper presents a comparative study of LCA methods. In this...
Article 37th International Conference on Computers and Industrial Engineering 2007, Alexandria, 20 October 2007 through 23 October 2007 ; Volume 2 , 2007 , Pages 1406-1409 ; 9781627486811 (ISBN) ; Haji, R ; Sharif University of Technology
This paper considers a two-level supply chain consisting of one warehouse and a number of identical retailers. Unlike the common practice which determines the optimal ordering policy according to inventory costs only, in this model we consider the transportation cost as well. We suppose that the delivery of each order from the warehouse to any retailer is made by a single vehicle without splitting. We also assume that there are three types of vehicles which are defined as small, medium and large. Each type has its own fixed cost, variable cost, and the capacity size. We assume that the demand rate at each retailer is known and the demand is confined to a single item. Shortages are allowed...
Article Environmental Progress and Sustainable Energy ; Volume 34, Issue 3 , 2015 , Pages 850-857 ; 19447442 (ISSN) ; Moradi, M. A ; Sharif University of Technology
John Wiley and Sons Inc 2015
This study presents a cost-benefit analysis of energy saving strategies for the commercial sector inTehran City. The article includes a discussion of the estimated energy demand for various energy saving scenarios. The cost-benefit analysis was performed separately for seven energy-saving scenarios based on the energy demand and supply forecasting model. According to which, energy demand of the commercial sector was considered as final consumption, which is a function of different parameters such as number of commercial units, number of electric vehicles, volume of commercial activities, labor force, etc. The research findings indicated that all of the proposed scenarios are economically...
Article 30th Congress of the International Council of the Aeronautical Sciences, ICAS 2016, 25 September 2016 through 30 September 2016 ; 2016 ; 9783932182853 (ISBN) ; Farkhondeh, F ; Khalili, N ; Abedian, A ; Sharif University of Technology
International Council of the Aeronautical Sciences 2016
Maintenance costs in airlines change as time passes. As airplane ages, it needs more often and more expensive checks. Due to these growing expenses, airlines are getting more interested in cost analysis. Under financial pressure, they avoid buying new airplanes and try to maintain the old ones, but sometimes try to cut the maintenance costs by ignoring or delaying some checks. In other words, they are more disposed to spend small amount of money frequently through time, than to spend a great deal on a new airplane with low maintenance costs. Therefore, in such situations, the following questions raise that what solution is more efficient as we look dynamically to the system? For answering...
Article 2009 International Conference on Computers and Industrial Engineering, 6 July 2009 through 9 July 2009 ; 2009 , Pages 857-862 ; 9781424441365 (ISBN) ; Haji, R ; Haji, A ; Sharif University of Technology
This paper attempts to develop the optimal solution for an inventoryproblem consisting of a single machine which produces items some of which may bedefective. We assume that no shortages are allowed and all defective items areto be reworked. Setup cost for rework and waiting time of defectives areconsidered. We consider two different policies where in the first policy in eachcycle after the regular production the machine is setup for the rework ofdefectives of the same cycle. In the second policy several cycles constitute aperiod. All the defectives produced in the period are reworked in the last cycleof that period. At the end of the rework cycle the whole process starts allover again. One...
Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 227, Issue 11 , 2013 , Pages 1685-1700 ; 09544100 (ISSN) ; Jafari, M. H ; Sharif University of Technology
Cost estimation plays an essential role in the development of aerospace systems that are perhaps the most complex, time- and labor-consuming ones. Regarding this matter, it is unavoidable to take a systematic approach to build a realistic model through a deliberative, heuristical and easy-to-do process in the early stages of design. In the current study, complexity index theory is utilized to develop a heuristic complexity-based method to estimate various costs of aerospace systems. This method promises to be logically and practically more reliable and accurate than classical parametric methods. Logically, manipulating a group of parameters, instead of only one or two, reduces the...
Article International Journal of Computational Intelligence and Applications ; Volume 11, Issue 2 , June , 2012 ; 14690268 (ISSN) ; Beigy, H ; Sharif University of Technology
In this paper, we introduce a new hybrid learning algorithm, called DTGP, to construct cost-sensitive classifiers. This algorithm uses a decision tree as its basic classifier and the constructed decision tree will be pruned by a genetic programming algorithm using a fitness function that is sensitive to misclassification costs. The proposed learning algorithm has been examined through six cost-sensitive problems. The experimental results show that the proposed learning algorithm outperforms in comparison to some other known learning algorithms like C4.5 or naïve Bayesian
Article 2009 International Conference on Computers and Industrial Engineering, CIE 2009, 6 July 2009 through 9 July 2009, Troyes ; 2009 , Pages 902-906 ; 9781424441365 (ISBN) ; Pirayesh Neghab, M ; Haji, A ; Sharif University of Technology
The purpose of this paper is to adopt and analyze a new ordering policycalled one-for-one-period policy in a multi-echelon supply chain consisting ofone retailer and a series of TV suppliers. The main advantage of adopting theone-for-one-period (7,7) ordering policy for retailers is the elimination ofuncertainty for supplier which leads to total elimination of the safety stocksat all suppliers. This in turn leads to the reduction of the total system costsand in case any supplier's ordering cost is negligible it can even eliminate theneed for him to carry any inventory. In addition to this advantage, thenumerical results show that the application of this new policy for the retailerleads to...
Article Journal of Physics A: Mathematical and Theoretical ; Volume 52, Issue 46 , 2019 ; 17518113 (ISSN) ; Clivaz, F ; Vitagliano, G ; Erker, P ; Rezakhani, A ; Huber, M ; Friis, N ; Sharif University of Technology
Institute of Physics Publishing 2019
Correlations lie at the heart of almost all scientific predictions. It is therefore of interest to ask whether there exist general limitations to the amount of correlations that can be created at a finite amount of invested energy. Within quantum thermodynamics such limitations can be derived from first principles. In particular, it can be shown that establishing correlations between initially uncorrelated systems in a thermal background has an energetic cost. This cost, which depends on the system dimension and the details of the energy-level structure, can be bounded from below but whether these bounds are achievable is an open question. Here, we put forward a framework for studying the...
Article 2004 International Conference on Power System Technology, POWERCON 2004, 21 November 2004 through 24 November 2004 ; Volume 1 , 2004 , Pages 856-861 ; 0780386108 (ISBN) ; Fotuhi Firuzabad, M ; Parniani, M ; Sharif University of Technology
The electric power industry around the world is presently undergoing considerable changes with respect to structure, operation and regulation. Distributed generation is expected to play a major role in this new environment One the main benefits of DG is to enhance system reliability as it can restore power to the separated or bottle-necked part of distribution system in case of a contingency occurs. This paper presents an approach to examine and evaluates the applicability and customer interruption cost analysis in DG-connected distribution system in a specified planning horizon. The impacts on customer interruption cost reduction of different load growth rate, DG location and different...
Article World Cement ; Volume 34, Issue 7 , 2003 , Pages 99-105 ; 02636050 (ISSN) ; Kakuei, A ; Sharif University of Technology
The upgradation of the Kerman cement plant in Iran was discussed. It produces type 2,5 and pozzolanic cements which constitute almost 4.2% of the cement used in Iran. A short description of the process used, and some observations and recommendations about the plant were also provided
Article IEEE Transactions on Power Systems ; Volume 18, Issue 1 , 2003 , Pages 279-287 ; 08858950 (ISSN) ; Farrokhzad, D ; Modarres, M ; Sharif University of Technology
A new model for long-term operation of hydrothermal power systems is introduced and a method for obtaining an optimal solution is also developed. We assume that reservoir inflows and energy demand are stochastic and all units are exposed to random outages. The objective is to minimize the total cost of the system as well as the expected interruption cost of energy (EIC) during a given planning horizon. This goal is reached through determination of hydroplant discharges, thermal units energy output, and the system reliability level simultaneously. In fact, we integrate long-term hydrothermal system operation planning and system reliability determination in a unified model. Since the resulting...
Article IEEE Power Engineering Review ; Volume 22, Issue 11 , 2002 , Pages 59- ; 02721724 (ISSN) ; Farrokhzad, D ; Modarres, M ; Sharif University of Technology
A new model for long-term operation of hydrothermal power systems is introduced, and a method for obtaining an optimal solution is developed. We assume both reservoir inflows and energy demand are stochastic and all units are exposed to random outages. The objective is to minimize the total cost of the system as well as the expected interruption cost of energy (EIC) during a given planning horizon. This goal is reached through simultaneous determination of hydro plant discharges, thermal units energy output, and the system reliability level. Long-term hydrothermal system operation planning and system reliability determination are integrated in a unified model. Since the resulting model is a...
Article International Review of Electrical Engineering ; Vol. 5, issue. 3 , 2010 , p. 1297-1306 ; ISSN: 18276660 ; Ehsan, M ; Fotuhi-Firuzabad, M ; Akhavein, A ; Sharif University of Technology
A method for clearing energy and reserve market in an aggregated framework is presented in this paper. The objective function of the optimization problem considers offered costs for energy and reserve requirements, the cost of nondelivery energy and the cost of nondelivery reserve. Incorporating these costs in the objective function, the proposed algorithm can obtain a solution in which the market required energy and reserve capacities are assigned to generating units with lower costs and higher response reliability. A new method based on optimal selection of nondelivery compensation alternatives is proposed to determine the mentioned costs. The proposed procedure provides incentives for...
Article 29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014 ; 7-12 September , 2014 ; ISBN: 3932182804 ; Shadaab, N ; Abedian, A ; Tanara, A. K ; Sharif University of Technology
Ways to reduce an airline's cost has been studied for years. In fact, in order to achieve this goal, ones need to know different types of airline's costs including; fuel and oil, maintenance, Ticketing, passenger services, etc. and their impact on the total cost of an airline. According to announcement of ICAO , "maintenance cost (about 11% of total cost) is the second major cost after fuel and oil". Therefore, this may attract airline owners' attention to find ways to control maintenance cost and eventually the total cost of an airline. Though, there are many systematic approaches to analyze cost reduction and making policies, in this article, SD modeling is applied to develop a...
Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 6 , December , 2007 , Pages 593-602 ; 10286284 (ISSN) ; Ehsan, M ; Fotuhi Firuzabad, M ; Ahmadi Khatir, A ; Bigdeli, N ; Sharif University of Technology
A new approach for optimal reserve determination and cost allocation in the pool-based and disaggregated market model using a well-being framework is presented in this paper. In the proposed method, customers have the chance to specify the risk level which they are willing to accept. Firstly, the energy market is cleared, and afterwards the reserve market is cleared such that the required risk levels of different customers are satisfied. Then, according to the required risk levels and the provided reserve, the cost of reserve is allocated between the different customers with different reliability requirements. For fairly managing the shortage between different customers in the real time...
Article 2005 IEEE Aerospace Conference, Big Sky, MT, 5 March 2005 through 12 March 2005 ; Volume 2005 , 2005 ; 1095323X (ISSN); 0780388704 (ISBN); 9780780388703 (ISBN) ; Kosari, A. R ; Jokar, S ; Sharif University of Technology
A new methodology has been proposed which offers a systematic approach to use the so called "performance index" or cost function as the basic tool to incorporate the dynamics of the aircraft in the process of trajectory planning. Moreover, by using non-dimensional parameters a better understanding of the dynamic terms are provided. © 2005 IEEE