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    A scatter search algorithm for RCPSP with discounted weighted earliness-tardiness costs

    , Article Life Science Journal ; Volume 8, Issue 2 , 2011 , Pages 634-640 ; 10978135 (ISSN) Khalilzadeh, M ; Kianfar, F ; Ranjbar, M ; Sharif University of Technology
    In this paper, we study a resource-constrained project scheduling problem in which a set of project activities have due dates. If the finish time of each one of these activities is not equal to its due date, an earliness or a tardiness cost exists for each tardy or early period. The objective is to minimize the sum of discounted weighted earliness-tardiness penalty costs of these activities. Scatter Search algorithm is used to deal with this extended form of resource-constrained project scheduling problem. Our implementation of Scatter Search integrates the advanced methods such as dynamic updating of the reference set and the use of frequency-based memory within the diversification... 

    Observation of a crossover in kinetic aggregation of Palladium colloids

    , Article Applied Surface Science ; Volume 353 , 2015 , Pages 1143-1149 ; 01694332 (ISSN) Ghafari, M ; Ranjbar, M ; Rouhani, S ; Sharif University of Technology
    Elsevier  2015
    We use field emission scanning electron microscope (FE-SEM) to investigate the growth of palladium colloids over the surface of thin films of WO3/glass. The film is prepared by Pulsed Laser Deposition (PLD) at different temperatures. A PdCl2 (aq) droplet is injected on the surface and in the presence of steam hydrogen the droplet is dried through a reduction reaction process. Two distinct aggregation regimes of palladium colloids are observed over the substrates. We argue that the change in aggregation dynamics emerges when the measured water drop Contact Angel (CA) for the WO3/glass thin films passes a certain threshold value, namely CA ≈ 46°, where a... 

    An efficient algorithm for solving bi-objective fuzzy job-shop scheduling problems by genetic algorithms and data mining

    , Article Amirkabir (Journal of Science and Technology) ; Volume 15, Issue 58 D , 2004 , Pages 570-591 ; 10150951 (ISSN) Rabbani, M ; Moghaddam, R. T ; Ranjbar, M ; Sharif University of Technology
    This paper presents a meta-heuristic algorithm for solving bi-objective fuzzy job shop scheduling problems. These objectives are to minimize the makespan and minimize the early and late penalty. Processing time and due date are considered as fuzzy triangular numbers. This paper also introduces a novel use of data mining algorithm for solving of combinatorial optimization problems. The proposed algorithm combines genetic algorithms and an attribute-oriented induction algorithm, which is much quicker than previous methods providing the optimal solution. By considering the structure of proposed algorithm, the whole feasible solutions of a special job shop-scheduling problem are considered as a... 

    Colouration process of colloidal tungsten oxide nanoparticles in the presence of hydrogen gas

    , Article Applied Surface Science ; Volume 258, Issue 24 , 2012 , Pages 10089-10094 ; 01694332 (ISSN) Tahmasebi Garavand, N ; Ranjbar, M ; Mahdavi, S. M ; Iraji Zad, A ; Sharif University of Technology
    Elsevier  2012
    In this study, tungsten oxide nanoparticles were fabricated by pulsed laser ablation (PLA) of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.2 g/lit PdCl 2 solution was added to activate the solution against the hydrogen gas. Dynamic light scattering and X-ray photoelectron spectroscopy were used to measure the average size and the surface chemical composition of the synthesized nanoparticles, respectively. The aim is to investigate the influence of hydrogen exposure time on colouration process of colloidal nanoparticles. According to optical measurements, hydrogen bubbling into the produced colloidal Pd-WO 3 led to formation of... 

    The effect of operating temperature on gasochromic properties of amorphous and polycrystalline pulsed laser deposited WO 3 films

    , Article Sensors and Actuators, B: Chemical ; Volume 169 , July , 2012 , Pages 284-290 ; 09254005 (ISSN) Garavand, N. T ; Mahdavi, S. M ; Zad, A. I ; Ranjbar, M ; Sharif University of Technology
    In this study, tungsten oxide films were synthesized by pulsed laser deposition (PLD) method. The as-deposited films were annealed at a temperature of 250 and 350°C in air for 1 h. The surface morphology, microstructure, crystalline phase and chemical composition of the as-prepared and annealed films were characterized by SEM, XRD and XPS techniques, respectively. Deposition of Pd nanoparticles onto the tungsten oxide surface was performed by hydrogen reduction of a drop-drying PdCl 2 solution onto a WO 3 surface at 60°C. The influence of the annealing temperature on microstructure and gasochromic performance as well as the effect of operating temperature is presented in this work. Results... 

    A modified PSO algorithm for minimizing the total costs of resources in MRCPSP

    , Article Mathematical Problems in Engineering ; Volume 2012 , 2012 ; 1024123X (ISSN) Khalilzadeh, M ; Kianfar, F ; Shirzadeh Chaleshtari, A ; Shadrokh, S ; Ranjbar, M ; Sharif University of Technology
    We introduce a multimode resource-constrained project scheduling problem with finish-to-start precedence relations among project activities, considering renewable and nonrenewable resource costs. We assume that renewable resources are rented and are not available in all periods of time of the project. In other words, there is a mandated ready date as well as a due date for each renewable resource type so that no resource is used before its ready date. However, the resources are permitted to be used after their due dates by paying penalty costs. The objective is to minimize the total costs of both renewable and nonrenewable resource usage. This problem is called multimode resource-constrained... 

    Electronic structure and morphological study of BaTiO 3 film grown by pulsed-laser deposition

    , Article Materials Letters ; Volume 72 , April , 2012 , Pages 107-109 ; 0167577X (ISSN) Ahadi, K ; Mahdavi, S. M ; Nemati, A ; Tabesh, M ; Ranjbar, M ; Sharif University of Technology
    The morphological characteristics and electronic structure of the BaTiO 3 films grown by pulsed-laser deposition technique have been investigated. AFM and FE-SEM images reveal columnar growth characteristic of these films. Utilizing spectrophotometer, optical band gap of the films were reckoned to be about 3.76 eV. Both dα/dE and PL vs. E plots reveal numerous luminance states in the gap. Despite the presence of many luminance faults in the gap, cations manage to preserve their electronic states  

    The evolution of catalyst layer morphology and sub-surface growth of CNTs over the hot filament grown Fe - Cr thin films

    , Article Applied Surface Science ; Volume 257, Issue 5 , 2010 , Pages 1511-1515 ; 01694332 (ISSN) Akbarzadeh Pasha, M ; Ranjbar, M ; Vesaghi, M. A ; Shafiekhani, A ; Sharif University of Technology
    In this study a hot filament chemical vapour deposition (HFCVD) technique was used to prepare Fe-Cr films on Si substrate as catalysts for thermal CVD (TCVD) growing of carbon nanotubes (CNTs) from liquid petroleum gas (LPG) at 800 °C. To characterize the catalysts or CNTs, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy were used. The XPS spectra obtained at different stages of Ar+ sputtering revealed that in the depth of catalyst layers, the relative Fe-Cr concentrations are higher than the top-surface. SEM images of samples after TCVD indicate a significant CNT growing at the backside of catalyst... 

    Diffusion and segregation of substrate copper in electrodeposited Ni-Fe thin films

    , Article Journal of Alloys and Compounds ; Volume 443, Issue 1-2 , 2007 , Pages 81-86 ; 09258388 (ISSN) Ahadian, M. M ; Iraji zad, A ; Nouri, E ; Ranjbar, M ; Dolati, A ; Sharif University of Technology
    The Cu surface segregation is investigated in the electrodeposited Ni-Fe layers using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS) and atomic force microscopy (AFM). The results indicate that Cu segregation and accumulation take place in areated and deareated baths and the amount of segregated copper increases after air exposure. This phenomenon is explained by lower interfacial tension of the Cu in comparison with Ni and Fe. Our results reveal more surface segregation in the electrodeposit than vacuum reported results. This should be due to interface charging and higher surface diffusion in applied potential. The effect of... 

    Market power monitoring in electricity market by using market simulation

    , Article 2006 IEEE Power India Conference, New Delhi, 10 April 2006 through 12 April 2006 ; Volume 2005 , 2005 , Pages 509-514 ; 0780395255 (ISBN); 9780780395251 (ISBN) Soleymani, S ; Ranjbar, A. M ; Jafari, A ; Shirani, A. R ; Ranjbar, M ; Sharif University of Technology
    This paper describes a new method for analyzing the bidding strategies of Generating Companies (GENCOs) in the Independent System Operator (ISO) point of view. ISO uses these results to detect the participants that have the potential for market power or actual exercise of market power. ISO models all GENCOs with perfect information. The proposed methodology uses the marginal cost of GENCOs as an initial point for bidding strategies of GENCOs and improves bidding strategies based on the objective function of GENCOs, the state of them in each hour of the day and with regard to ISO's market clearing problem. ISO tries to maximize the social welfare or minimize consumer's payments. The model... 

    Laboratory evaluation of nitrogen injection for enhanced oil recovery: Effects of pressure and induced fractures

    , Article Fuel ; Volume 253 , 2019 , Pages 607-614 ; 00162361 (ISSN) Fahandezhsaadi, M ; Amooie, M. A ; Hemmati Sarapardeh, A ; Ayatollahi, S ; Schaffie, M ; Ranjbar, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Nitrogen has emerged as a suitable alternative to carbon dioxide for injection into hydrocarbon reservoirs worldwide to enhance the recovery of subsurface energy. Nitrogen typically costs less than CO2 and natural gas, and has the added benefit of being widely available and non-corrosive. However, the underlying mechanisms of recovery following N2 injection into fractured reservoirs that make up a large portion of the world's oil and gas reserves are not well understood. Here we present the laboratory results of N2 injection into carbonate rocks acquired from a newly developed oil reservoir in Iran with a huge N2-containing natural gas reservoir nearby. We investigate the effectiveness of N2... 

    Enhanced performance of planar perovskite solar cells using TiO2/SnO2 and TiO2/WO3 bilayer structures: Roles of the interfacial layers

    , Article Solar Energy ; Volume 208 , 2020 , Pages 697-707 Kazemzadeh Otoufi, M ; Ranjbar, M ; Kermanpur, A ; Taghavinia, N ; Minbashi, M ; Forouzandeh, M ; Ebadi, F ; Sharif University of Technology
    Elsevier Ltd  2020
    In planar perovskite solar cells (PSCs), engineering the extraction and recombination of electron–hole pairs by modification of the electron transport layer (ETL)/perovskite interface is very vital for obtaining high performance. The main idea here is to improve properties of the TiO2/perovskite interface by inserting an ultra-thin layer (UTL) of WO3 or SnO2 with the thickness of less than 10 nm by RF magnetron sputtering method. The structural and electrical characteristics of the samples were tested by XRD, AFM, FE-SEM, Mott-Schottky analysis, UV–Vis spectroscopy, J-V characterization and electrochemical impedance spectroscopy (EIS). It was found that the bilayer structured ETLs exhibit...