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    The effect of injection parameters on dimensional accuracy of wax patterns for investment casting

    , Article Journal of Computational and Applied Research in Mechanical Engineering ; Volume 9, Issue 2 , 2020 , Pages 313-322 Barati, E ; Akbari, J ; Sharif University of Technology
    Shahid Rajaee Teacher Tarining University (SRTTU)  2020
    Thermal expansion and hot deformation are two phenomena causing dimensional errors in investment casting. This error occurs in dimensions between the die and wax pattern. Therefore, the wax's thermo-physical and thermo-mechanical properties, the metal die features, and the process parameters affect the dimensions of the wax pattern. Some important effective process parameters are the injection temperature, die temperature, and holding time. In this paper, the effect of injection parameters on the dimensional accuracy of the wax model created by a metallic die is studied. The Taguchi formulation based on the design of experiments is applied to obtain the optimum condition in achieving the... 

    Preemptive multi-skilled resource investment project scheduling problem: mathematical modelling and solution approaches

    , Article Computers and Chemical Engineering ; Volume 96 , 2017 , Pages 55-68 ; 00981354 (ISSN) Javanmard, S ; Afshar Nadjafi, B ; Akhavan Niaki, S. T ; Sharif University of Technology
    Many chemical production systems encounter with a functionally flexible workplace which need multi-skilled workers. This research integrates the multi-skilled project scheduling problem with the resource investment problem which aims to obtain concurrent optimal policy of project scheduling and skills’ recruitment. The objective of the proposed model is minimization of total recruitment cost for different levels of the skills. An integer programming formulation is developed for the problem, and it is validated through solving several small scale instances using the GAMS software. To tackle real-life problem scales, a genetic-based and a particle-swarm-based algorithm with calibrated... 

    Investment cost optimization for industrial project portfolios using technology mining

    , Article Technological Forecasting and Social Change ; Volume 138 , 2019 , Pages 243-253 ; 00401625 (ISSN) Azimi, S ; 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... 

    A new approach for solving resource constrained project scheduling problems using differential evolution algorithm

    , Article International Journal of Industrial Engineering Computations ; Volume 7, Issue 2 , 2016 , Pages 205-216 ; 19232926 (ISSN) Eshraghi, A ; Sharif University of Technology
    Growing Science 
    One subcategory of project scheduling is the resource constrained project scheduling problem (RCPSP). The present study proposes a differential evolution algorithm for solving the RCPSP making a small change in the method to comply with the model. The RCPSP is intended to program a group of activities of minimal duration while considering precedence and resource constraints. The present study introduces a differential evolution algorithm and local search was added to improve the performance of the algorithm. The problems were then solved to evaluate the performance of the algorithm and the results are compared with genetic algorithm. Computational results confirm that the differential... 

    Applicability of ARIMA models for investigating the effects of Technology spillover on Car Manufacturing Companies' performance

    , Article 8th International Conference on Industrial Engineering and Operations Management, IEOM 2018, 6 March 2018 through 8 March 2018 ; Volume 2018-March , 2018 ; 21698767 (ISSN); 9781532359446 (ISBN) Khorshidnam, M ; Karami, A ; Cyrus, K.M ; Eaton; INFORMS (Institute for Operations Research and Management Sciences); Siemens ; Sharif University of Technology
    IEOM Society  2018
    The present study seeks to investigate the effects of technology spillover on the performance of automobile companies. In short, technology spillover is an opportunity to transfer and exploit and obtain information, technology or technical know-how, without prior planning. One of the most important indicators in evaluation of cars' manufacturing companies' performance is sales; hence, this study focused on sales variable and took it as a representative of Technology spillover. To this aim, the sales data were collected fromthe domestic car manufacturing companies. For this mean, sales' pattern during ten years is recognized using Seasonal ARIMA (S-ARIMA) model. Akaike Information Criterion... 

    Designing an Algorithm for the Resource Investment Problem Considering Calendar

    , M.Sc. Thesis Sharif University of Technology Parvizi, Saeed (Author) ; Shadrokh, Shahram (Supervisor)
    Project scheduling problems can be divided into different categories which one of the most important of them is resource investment problem. In this problem we are faced with a time limit for completion but resources are available unlimitedly and can be allocated to the project by specific cost. One of the most important constraints in real problems is the times that resources are available. In this research, resource investment problem considering calendar for resources has been investigated. Since resource investment problem is NP-Hard, after a brief overview of the different solutions, we used genetic algorithm to solve this problem. For this purpose, after determining chromosome... 

    A genetic algorithm for resource investment project scheduling problem, tardiness permitted with penalty

    , Article European Journal of Operational Research ; Volume 181, Issue 1 , 2007 , Pages 86-101 ; 03772217 (ISSN) Shadrokh, S ; Kianfar, F ; Sharif University of Technology
    In this paper a genetic algorithm for solving a class of project scheduling problems, called Resource Investment Problem, is presented. Tardiness of project is permitted with defined penalty. Elements of algorithm such as chromosome structure, unfitness function, crossover, mutation, immigration and local search operations are explained. The performance of this genetic algorithm is compared with the performance of other published algorithms for Resource Investment Problem. Also 690 problems are solved and their optimal solutions are used for the performance tests of the genetic algorithm. The tests results are quite satisfactory. © 2006 Elsevier B.V. All rights reserved  

    Pilot plant and their rule in chemical industries

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Babazadeh, F ; Haddadi, A. M ; Kazemini, M ; Sharif University of Technology
    With regard to petrol, petrochemical and chemical industries extension in Iran and with regard to growth of agreements in these field and huge investment payments for different engineering activities and technology transfer, we need to evaluate each of these projects essentially and scientifically to reach the success. For this purpose we need to investigate the chain from science to market. On of the middle cycle of the chain are pilot plants, which have key rule for success of project. In this work after introducing pilot plant and explanation of their aims and characteristics, we allude the rule and situation of pilot plant for getting technology and transfer in chemical industries and... 

    Short-term market power assessment in a long-term dynamic modeling of capacity investment

    , Article IEEE Transactions on Power Systems ; Volume 28, Issue 2 , October , 2013 , Pages 626-638 ; 08858950 (ISSN) Hasani Marzooni, M ; Hosseini, S. H ; Sharif University of Technology
    This paper proposes a dynamic time simulation model for long-term generation capacity investment decisions in the presence of either perfect or imperfect electricity market. The model is based on system dynamics concept in which the dynamics of capacity construction is traced using the forecast of electricity price cleared in the short-term electricity market. Both the perfect and oligopolistic competitions are considered and a market power index is defined to evaluate the competition level of the electricity market. The short-term and long-term dynamic analysis are used to represent the generation firms' behavior in bidding strategy and capacity investment, respectively. Both possibilities... 

    Robust transmission expansion planning considering private investments maximization

    , Article 2016 IEEE International Conference on Power System Technology, POWERCON 2016, 28 September 2016 through 1 October 2016 ; 2016 ; 9781467388481 (ISBN) Ranjbar, H ; Hosseini, S. H ; Kasebahadi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Deregulation in power systems has created new uncertainties and increased the previous ones. The presence of these uncertainties, high investment costs, and long period investment return cause the transmission network to remain monopoly and the private investors not being interested in investing in this section. This paper presents a new approach for transmission expansion planning (TEP) in order to maximize private investment absorption. The robust optimization method is used to model the inherent uncertainties associated with the estimated investment cost of candidate lines and the forecasted system load. The genetic algorithm (GA) is, also, utilized as the methodology to solve the... 

    MILP model for integrated expansion planning of multi-carrier active energy systems

    , Article IET Generation, Transmission and Distribution ; Volume 13, Issue 7 , 2019 , Pages 1177-1189 ; 17518687 (ISSN) Ghasemi, H ; Aghaei, J ; Gharehpetian, G. B ; Safdarian, A ; Sharif University of Technology
    Institution of Engineering and Technology  2019
    In growing economic energy systems, the interdependency of various energy infrastructures has led to a change in countries' policies in their expansion planning of energy networks. In this study, a mixed-integer non-linear programming (MINLP) model is proposed for expansion planning of the multi-carrier systems including electricity and gas distribution networks. The optimal planning determines the best location, time, and alternative for network assets in order to minimise investment costs and reduce losses. Also, as another distinctive feature of this study, given the integration of electricity and gas distribution networks and the complexity of the problem, a new MILP model using... 

    The impact of customer knowledge on the organizational performance: a system dynamics approach

    , Article Kybernetes ; 2021 ; 0368492X (ISSN) Bidgoli, S. D ; Owlia, M. S ; Isaai, M. T ; Sharif University of Technology
    Emerald Group Holdings Ltd  2021
    Purpose: The purpose of this research was to model the impact of customer knowledge on the performance of organization with a focus on information technology industry. Furthermore, it is intended to analyze the effect of customer knowledge investment on the performance measures, by reviewing investment policies. Design/methodology/approach: The relationship between customer knowledge and performance measures was specified using literature review and grounded theory method. The system dynamics approach was then applied to analyze the impact of the customer knowledge on the performance measures. Findings: This study provided a dynamic model on the causal relationship between customer knowledge... 

    A genetic algorithm for resource investment problems, enhanced by the revised Akpan method

    , Article Scientia Iranica ; Volume 12, Issue 1 , 2005 , Pages 90-98 ; 10263098 (ISSN) Shadrokh, S ; Kianfar, F ; Sharif University of Technology
    Sharif University of Technology  2005
    In this paper, a genetic algorithm for solving a class of project scheduling problems, called Resource Investment Problems, is presented. Tardiness of the project is permitted with a defined penalty. The decision variables are the level of resources and the start times of the activities. The objective is to minimize the sum of resources and delay penalty costs, subject to the activities' precedence relations and some other constraints. A revised form of the Akpan heuristic method for this problem is used to find better chromosomes. Elements of the algorithm, such as chromosome structure, unfitness function, crossover, mutation, immigration and local search operations, are explained. The... 

    Resource investment problem with discounted cash flows

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 18, Issue 1 , 2005 , Pages 53-64 ; 1728-144X (ISSN) Najafi, A. A ; Akhavan Niaki, S. T ; Sharif University of Technology
    Materials and Energy Research Center  2005
    A resource investment problem is a project-scheduling problem in which the availability levels of the resources are considered as decision variables and the goal is to find a schedule, and resource requirement levels, such that some objective function optimizes. In this paper, we consider a resource investment problem in which the goal is to maximize the net present value of the project cash flows. We call this problem as Resource Investment Problem with Discounted Cash Flows (RIPDCF) and we develop a heuristic method to solve it. Results of several numerical examples show that the proposed method performs relatively well  

    Dynamic analysis of various investment incentives and regional capacity assignment in Iranian electricity market

    , Article Energy Policy ; Volume 56 , 2013 , Pages 271-284 ; 03014215 (ISSN) Hasani Marzooni, M ; Hosseini, S. H ; Sharif University of Technology
    This paper develops a system dynamics model to analyze the impacts of different kinds of capacity payment as investment incentive mechanisms in Iranian electricity market. Since it is aimed that the incurred capital and operating costs of generation technologies be recovered in Iranian electricity pool, the noncompetitive capacity payment mechanism has been introduced for this purpose in order to encourage new investments in electric power generation system. In the current mechanism, the capacity payments are designated to the generating units in the whole country electricity market. An annual base value of capacity payment is proposed based on recovering the capital cost of a benchmark... 

    Presenting a rule based loan evaluation expert system

    , Article 4th International Conference on Information Technology-New Generations, ITNG 2007, Las Vegas, NV, 2 April 2007 through 4 April 2007 ; 2007 , Pages 495-502 ; 0769527760 (ISBN) ; 9780769527765 (ISBN) Houshmand, M ; Daneshvar Kakhki, M ; Sharif University of Technology
    A core process in investment banks is evaluation of loan requests. In this paper we have presented the development of a rule based expert system for evaluation of loan request. The purpose of system is to evaluate the loan request and do some sensitivity analyses on the evaluation result to find the critical criteria. To achieve this purpose, Inference engine works both forward (evaluation) and backward chaining (sensitivity analysis). This system is designed for the Iranian bank of Industry and Mine. © 2007 IEEE  

    Addressing the growth failure of the oil economies: The role of financial development

    , Article Quarterly Review of Economics and Finance ; Volume 46, Issue 5 , 2007 , Pages 726-740 ; 10629769 (ISSN) Nili, M ; Rastad, M ; Sharif University of Technology
    The oil exporting countries have experienced a relatively continuous fall in GDP per capita over the last 30 years. This is in spite of benefiting from a more than average of the rest of the world investment rate. The findings of this paper, report a lower level of financial development for the oil economies when compared with the rest of the world. We will show in this paper that the higher rate of investment of the oil economies can be explained mainly by the oil revenues and surprisingly, financial development has a net dampening effect on investment for these economies. The paper also shows that the weakness of financial institutions, contributes to the poor performance of economic... 

    A genetic algorithm for resource investment problem with discounted cash flows

    , Article Applied Mathematics and Computation ; Volume 183, Issue 2 , 2006 , Pages 1057-1070 ; 00963003 (ISSN) Najafi, A. A ; Akhavan Niaki, S. T ; Sharif University of Technology
    A resource investment problem with discounted cash flows is a project scheduling problem in which the availability levels of the resources are considered decision variables and the goal is to find a schedule and resource requirement levels such that the net present value of the project cash flows optimizes. In this paper, we present a genetic algorithm to solve this problem. We explain the elements of the algorithm such as chromosome structure, fitness function, crossover, mutation, and local improvement operations and solve more than 220 problems with known optimal solutions to evaluate the performance of the proposed algorithm. The results of the experimentation are quite satisfactory. ©... 

    Market based criteria for transmission expansion planning

    , Article PECon2010 - 2010 IEEE International Conference on Power and Energy ; 2010 , p. 846-851 ; ISBN: 9781420000000 Kamyab, G ; Fotuhi-Firuzabad, M ; Rashidi-Nejad, M ; Sharif University of Technology
    In this paper, first, two new criteria, which are titled social welfare percent (SWP) and congestion cost percent (CCP), are defined for static transmission expansion planning in restructured power systems. Then by a simple example it will be shown that none of the already presented market-based criteria could completely and truly evaluate the transmission network expansion from market view. Hence the SWP and CCP criteria altogether are proposed to completely and truly evaluate the transmission network expansion. Then a least-investment cost expansion plan is searched that its SWP and CCP are in predefined acceptable limits. The results of applying of the proposed method are illustrated over... 

    Iran's oil development scenarios by 2025

    , Article Energy Policy ; Volume 56 , 2013 , Pages 612-622 ; 03014215 (ISSN) Abbaszadeh, P ; Maleki, A ; Alipour, M ; Maman, Y. K ; Sharif University of Technology
    Energy resources in Iran consist of the fourth largest oil reserves and the second largest natural gas reserves in the world. At present, due to political reasons, the investment trend does not go over well. Based on the Fifth Development Strategy, Iran needs $200 billion of investment in the country's first industry (i.e. oil), and given the objectives of the perspective document, the country needs more than $500 billion investment during the next 15 years. This paper examined Iran's energy status. Afterwards, oil future scenarios which developed by Research center of Iranian parliament, have been analyzed. Then four scenarios that express different modes of production and consumption are...