Search for: simulators
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    Adsorption onto zeolites: molecular perspective

    , Article Chemical Papers ; Volume 75, Issue 12 , 2021 , Pages 6217-6239 ; 03666352 (ISSN) Salmankhani, A ; Mousavi Khadem, S. S ; Seidi, F ; Hamed Mashhadzadeh, A ; Zarrintaj, P ; Habibzadeh, S ; Mohaddespour, A ; Rabiee, N ; Lima, E. C ; Shokouhimehr, M ; Varma, R. S ; Saeb, M. R ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    2D minerals are among key elements of advanced systems, but the need for understanding their interactions/reactions with materials and systems in which they are involved necessitates tracking their molecular and atomic monitoring. Zeolitic structures are microporous materials formed in the nature through volcanic activities or synthesis. Because of their outstanding physicochemical properties like cation exchange capacity and excellent adsorption properties, zeolites have found application in diverse chemical processes, e.g., gas adsorption, water purification, and wastewater treatment. Prediction of zeolite performance for a targeted application saves time and expense as such projection... 

    Understanding the nanoparticle-protein corona complexes using computational and experimental methods

    , Article International Journal of Biochemistry and Cell Biology ; Volume 75 , 2016 , Pages 162-174 ; 13572725 (ISSN) Kharazian, B ; Hadipour, N. L ; Ejtehadi, M. R ; Sharif University of Technology
    Elsevier Ltd 
    Nanoparticles (NP) have capability to adsorb proteins from biological fluids and form protein layer, which is called protein corona. As the cell sees corona coated NPs, the protein corona can dictate biological response to NPs. The composition of protein corona is varied by physicochemical properties of NPs including size, shape, surface chemistry. Processing of protein adsorption is dynamic phenomena; to that end, a protein may desorb or leave a surface vacancy that is rapidly filled by another protein and cause changes in the corona composition mainly by the Vroman effect. In this review, we discuss the interaction between NP and proteins and the available techniques for identification of... 

    Improving a computer networks course using the Partov simulation engine

    , Article IEEE Transactions on Education ; Volume 55, Issue 3 , 2012 , Pages 436-443 ; 00189359 (ISSN) Momeni, B ; Kharrazi, M ; Sharif University of Technology
    Computer networks courses are hard to teach as there are many details in the protocols and techniques involved that are difficult to grasp. Employing programming assignments as part of the course helps students to obtain a better understanding and gain further insight into the theoretical lectures. In this paper, the Partov simulation engine and experience using this engine in a computer networks course are discussed. Since 2009, various programming assignments based on the Partov system have been set to help students in their learning process. Student feedback has been very good; this has been quantified in two surveys in which a majority of students expressed their satisfaction with this... 

    XMulator: A listener-based integrated simulation platform for interconnection networks

    , Article 1st Asia International Conference on Modelling and Simulation - Asia Modelling Symposium 2007, AMS 2007, 27 March 2007 through 30 March 2007 ; 2007 , Pages 128-132 ; 0769528457 (ISBN); 9780769528458 (ISBN) Nayebi, A ; Meraji, S ; Shamaei, A ; Sarbazi Azad, H ; Al Dabass D ; Zobel R ; Abraham A ; Turner S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2007
    Simulation is perhaps the most cost-effective tool to evaluate the operation of a system under design. A flexible, easy to extend, fully object-oriented, and multilayered simulator for interconnection networks can be a very useful tool for multicomputer designers and researchers. It is so desirable to attach newly designed components to the existing models and to exploit detailed results. This paper presents XMulator, an object-oriented listener-based simulation environment for evaluating multicomputer interconnection networks. The simulator involves a toolbox of various network topologies, routing algorithms, switching techniques, and flexible router models. This work introduces a... 

    Model reference adaptive control design for a ducted fan air vehicle in vertical plane

    , Article Applied Mechanics and Materials, 21 November 2012 through 22 November 2012 ; Volume 225 , November , 2012 , Pages 331-337 ; 16609336 (ISSN) ; 9783037855065 (ISBN) Fadaeian, E ; Banazadeh, A ; Sharif University of Technology
    Ducted fan aerial vehicles have drawn many attentions in the world because of their successful involvement in non-traditional reconnaissance and surveillance missions. However, due to inherent dynamic uncertainties as well as inconsistent responses, significant control challenges are still to be addressed. In this study, a non-linear dynamic model for ducted fan is firstly proposed to be employed for control design. This model is then validated by performing a series of standard simulation scenarios. Afterwards, an adaptive control method, named as model reference is utilized to design perfect controllers in hover as well as vertical flight. The capability of the adaptive laws to update the... 

    Investigation of reinforced sic particles percentage on machining force of metal matrix composite

    , Article Modern Applied Science ; Volume 6, Issue 8 , 2012 , Pages 9-20 ; 19131844 (ISSN) Fathipour, M ; Zoghipour, P ; Tarighi, J ; Yousefi, R ; Sharif University of Technology
    MAS  2012
    In this study two-dimensional finite element models of Al/SiC metal matrix composites (MMC) by using of ABAQUS Explicit software are investigated. Chip formations and machining forces for three types of MMC with 5, 15 and 20% of SiC reinforcement particles were studied and compared with experimental data. The resulted chips in simulation and the generated chips in experiments have both continuous and saw tooth in appearance. On the other hand, the variation of the cutting forces with the cutting time in simulation and experiment have fluctuating diagram. This is due to the interaction between cutting tool and SiC particles during chip formation. ABAQUS explicit software was used for... 

    Static and dynamic neural networks for simulation and optimization of cogeneration systems

    , Article International Journal of Energy and Environmental Engineering ; Volume 2, Issue 1 , Mar , 2011 , Pages 51-61 ; 20089163 (ISSN) Zomorodian, R ; Rezasoltani, M ; Ghofrani, M. B ; Sharif University of Technology
    In this paper, the application of neural networks for simulation and optimization of the cogeneration systems has been presented. CGAM problem, a benchmark in cogeneration systems, is chosen as a case study. Thermodynamic model includes precise modeling of the whole plant. For simulation of the steady sate behavior, the static neural network is applied. Then using dynamic neural network, plant is optimized thermodynamically. Multi- layer feed forward neural networks is chosen as static net and recurrent neural networks as dynamic net. The steady state behavior of Excellent CGAM problem is simulated by MFNN. Subsequently, it is optimized by dynamic net. Results of static net have excellent... 

    Point to point continuum percolation in two dimensions

    , Article Journal of Statistical Mechanics: Theory and Experiment ; Volume 2016, Issue 10 , 2016 ; 17425468 (ISSN) Sadeghnejad, S ; Masihi, M ; Sharif University of Technology
    Institute of Physics Publishing  2016
    The outcome of the classic percolation approach is several power-law curves with some universal (critical) exponents. Here, the universality means that these power laws as well as their critical exponents, which control the global properties of a system, are independent of its details. Classic percolation considers the connectivity between two lines and two faces at opposite sides of a system in 2- and 3D problems, respectively; whereas, in practice (e.g. hydrocarbon formations), production and injection wells are represented by points (in 2D areal models) and lines (in 3D models). This study presents the results of Monte Carlo simulations of a 2D percolation model wherein the connection... 

    Robust simulation optimization using φ-divergence

    , Article International Journal of Industrial Engineering Computations ; Volume 7, Issue 4 , 2016 , Pages 517-534 ; 19232926 (ISSN) Moghaddam, S ; Mahlooji, H ; Sharif University of Technology
    Growing Science 
    We introduce a new robust simulation optimization method in which the probability of occurrence of uncertain parameters is considered. It is assumed that the probability distributions are unknown but historical data are on hand and using φ-divergence functionality the uncertainty region for the uncertain probability vector is defined. We propose two approaches to formulate the robust counterpart problem for the objective function estimated by Kriging. The first method is a minimax problem and the second method is based on the chance constraint definition. To illustrate the methods and assess their performance, numerical experiments are conducted. Results show that the second method obtains... 

    A system dynamics approach to the seismic resilience enhancement of hospitals

    , Article International Journal of Disaster Risk Reduction ; Volume 31 , 2018 , Pages 220-233 ; 22124209 (ISSN) Khanmohammadi, S ; Farahmand, H ; Kashani, H ; Sharif University of Technology
    Elsevier Ltd  2018
    In the aftermath of earthquakes, hospitals serve the critical role of treating casualties. In many cases, the key components of a hospital (i.e., the building, staff, medicine inventory, technical systems, and medical equipment) are affected by an earthquake. To handle the demand surge, affected hospitals should recover in an effective manner. Hospital recovery is a complex and dynamic process because each component requires specific types and amount of resources to recover. Furthermore, the recovery of each component not only affects its performance but also plays a role in the overall hospital recovery. Hospital administrators need to model the complex recovery process after a future... 

    Simulation of water purification using magnetically ultra-responsive micro- and nanoscavengers

    , Article Journal of Water Process Engineering ; Volume 24 , 2018 , Pages 63-73 ; 22147144 (ISSN) Asghari, E ; Moosavi, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
    Elsevier Ltd  2018
    Access to clean water is one of the challenges of the 21st century. Thus water purification is inevitable. One method of water treatment is purification by magnetic particles in the presence of magnetic field. The contaminants are attached to the magnetic particles and then by applying a magnetic field, magnetic particles and, thus, the pollutants can be collected. For the optimal design of a water treatment system, the effect of important parameters in the design, such as magnetic fields, particle size, and Reynolds number are determined numerically by modeling and simulating the water treatment process. Two methods are used to create the magnetic field: permanent magnet and coils. It is... 

    Effect of copper content on tensile mechanical properties of ternary NiTiCu alloy nanowire: molecular dynamics simulation

    , Article Materials Today: Proceedings ; Volume 5, Issue 1 , 2018 , Pages 1552-1555 ; 22147853 (ISSN) Fazeli, S ; Vahedpour, M ; Sadrnezhaad, K ; Sharif University of Technology
    Elsevier Ltd  2018
    Molecular dynamics (MD) simulation was used to study of mechanical properties of NiTiCu with different content of copper. It was shown that the percent composition of copper are significantly affects the stress-strain curves curve. The results showed that as the Cu content increased, the Yield Strength and Young's modulus decreased. © 2017 Elsevier Ltd  

    A hardwired discrete simulation algorithm

    , Article Scientia Iranica ; Volume 14, Issue 6 , 2007 , Pages 566-570 ; 10263098 (ISSN) Nojumi, M. H ; Sharif University of Technology
    Sharif University of Technology  2007
    The architecture of a hardwired simulator for implementation of a discrete event-driven simulation of digital systems at the logic level is presented. In the design of this system, attempts have been made to utilize techniques of high performance computing to have a system capable of simulating the digital circuits rapidly. The centralized event-driven simulation algorithm chosen here, has the advantages of being efficient and conceptually straightforward. The high reliability of the simulator has been taken care of through a collection of handshake signals between each two of the three main modules. © Sharif University of Technology, December 2007  

    A Monte Carlo simulation of nutrient diffusion and reaction in immobilized cell systems

    , Article Chemical Physics ; Volume 321, Issue 1-2 , 2006 , Pages 34-40 ; 03010104 (ISSN) Yari, B ; Khorasheh, F ; Kheirolomoom, A ; Sharif University of Technology
    In this study a Monte Carlo simulation was used to investigate the effect of cell reactivities and particle diffusivities in the cells and matrix on the diffusion and reaction rate constants in gel-immobilized cell systems with different spatial cell configurations. A variety of conditions were examined ranging from instantaneous to very slow reactions with reaction probabilities equal to or less than one, and diffusivity ratios bigger or smaller than one in a spherical domain. In the case of high reactivity (diffusion-limited), the simulation results indicated a decrease in the reaction rate constants when heterogeneity in the cell distribution was increased. In the case of low reactivity... 

    Axisymmetric and three-dimensional flow simulation of a mixed compression supersonic air inlet

    , Article Propulsion and Power Research ; Volume 9, Issue 1 , 2020 , Pages 51-61 Abedi, M ; Askari, R ; Sepahi Younsi, J ; Soltani, M. R ; Sharif University of Technology
    Elsevier Ltd  2020
    The flow through an axisymmetric supersonic mixed-compression air inlet has been simulated numerically to investigate the effects and the necessity of the three-dimensional (3D) modeling in comparison with the axisymmetric one. For this purpose, a supersonic inlet has been simulated numerically via axisymmetric and 3D CFD solvers, using the steady state Reynolds-averaged Navier-Stokes equations along with the SST k-ω turbulence model, for a free-stream Mach number of 2.0 and at zero degrees angle of attack. The grid for the 3D cases was a 14.4-degree sector, instead of a 360-degree domain one, with rotational periodic boundary condition for the side boundaries. The results show that both... 

    Large eddy simulations of a brine-mixing tank

    , Article 25TH International Conference on Offshore Mechanics and Arctic Engineering, OMAE 2006, Hamburg, 4 June 2006 through 9 June 2006 ; Volume 2006 , 2006 ; 0791837777 (ISBN); 9780791837771 (ISBN) Mousavi, S. M ; Zamankhan, P ; Sharif University of Technology
    Traditionally, solid-liquid mixing has always been regarded as an empirical technology with many aspects of mixing, dispersing and contacting where related to power draw. One important application of solid-liquid mixing is the preparation of brine from sodium formate. This material has been widely used as a drilling and completion fluid in challenging environments such as in the Barents Sea. In this paper large-eddy simulations, of a turbulent flow in a solid-liquid, baffled, cylindrical mixing vessel with a large number of solid particles, are performed to obtain insight into the fundamental aspects of a mixing tank. The impeller-induced flow at the blade tip radius is modeled by using the... 

    Stochastic ensemble pruning method via simulated quenching walking

    , Article International Journal of Machine Learning and Cybernetics ; Volume 10, Issue 7 , 2019 , Pages 1875-1892 ; 18688071 (ISSN) Taghavi, Z. S ; Akhavan Niaki, S. T ; Niknamfar, A. H ; Sharif University of Technology
    Springer Verlag  2019
    Inspired by an upward stochastic walking idea, a new ensemble pruning method called simulated quenching walking (SQWALKING) is developed in this paper. The rationale behind this method is to give values to stochastic movements as well as to accept unvalued solutions during the investigation of search spaces. SQWALKING incorporates simulated quenching and forward selection methods to choose the models through the ensemble using probabilistic steps. Two versions of SQWALKING are introduced based on two different evaluation measures; SQWALKINGA that is based on an accuracy measure and SQWALKINGH that is based on a human-like foresight measure. The main objective is to construct a proper... 

    Model enrichment: Concept, measurement, and application

    , Article Journal of Simulation ; Volume 6, Issue 2 , 2012 , Pages 125-140 ; 17477778 (ISSN) Yavari, E ; Roeder, T ; Sharif University of Technology
    Simplicity and validity are recognized as important attributes of an effective simulation model. However, some disagreement exists both on the definitions of these concepts and on quantitative measures for them. This paper introduces Enrichment Level (EL) for (simulation) models. The EL is a quantitative measure to compare the effectiveness of alternative models when used in a particular project. While there is no conceptual restriction on expanding the EL, it currently captures the bias, speed, variance, and scope of a model as the main contributing enrichment factors. This paper explores these factors and suggests a utility-based method to combine them according to the relative importance... 

    Estimating the parameters of weibull distribution using simulated annealing algorithm

    , Article Applied Mathematics and Computation ; Volume 183, Issue 1 , 2006 , Pages 85-93 ; 00963003 (ISSN) Abbasi, B ; Eshragh Jahromi, A. H ; Arkat, J ; Hosseinkouchack, M ; Sharif University of Technology
    Weibull distribution plays an important role in failure distribution modeling in reliability studies. It is a hard work to estimate the parameters of Weibull distribution. This distribution has three parameters, but for simplicity, a parameter is omitted and as a result, the estimation of the others will be easily done. When the three-parameter distribution is of interest, the estimation procedure will be quite boring. Maximum likelihood estimation is a good method, which is usually used to elaborate on the parameter estimation. The likelihood function formed for the parameter estimation of a three-parameter Weibull distribution is very hard to maximize. Many researchers have studied this... 

    Study Elongation of a Single Strend DNA on the Surface Under Potential Using Monte Carlo Simulation

    , M.Sc. Thesis Sharif University of Technology Kiani, Sedighe (Author) ; Parsafar, Gholamabbas (Supervisor) ; Tafazzoli, Mohsen (Supervisor) ; Ejtehadi, Mohammad Reza (Co-Advisor)
    In this project, the behavior of single strand DNA (ssDNA) that is end-tethred to surface (surface is covered with an layer of mercaptohexane ) through the Monte Carlo simulation has been investigated. To understand this behavior, a ssDNA has been studied through freely jointed chain (FJC) model with electrostatic, base paring, and base-pair stacking interaction. The concentration of sodium chloride salt in solution is 1 mM and the applied surface potential is -1.5 - +0.25 V. Computational results show that the ssDNA chain can have the following configurations: 1) “very closed”, 2) “closed”, and 3) “open” that considering the amount of energy, the mentioned configurations can be compared...