Search for: mathematical-models
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    Improvement of pierce-smith converter performance and reduction of splashing using smoothed particle hydrodynamics method

    , Article Advanced Science Letters ; Volume 19, Issue 2 , 2013 , Pages 425-428 ; 19366612 (ISSN) Lileh Koohi, A. H ; Halali, M ; Askari, M ; Sharif University of Technology
    Splashing in the Peirce Smith copper converter was investigated using the Smoothed Particle Hydrodynamics (SPH) method. A model 50 cm in diameter (one eighth of the actual convertor) was made to verify results. The ffect of air flow rate and the distance of air blowers from the surface were identified as two major contributors to splashing and their effect on splashing was investigated. Using C++ based on SPH method, a model, geometrically identical to the physical model, was designed for simulation and verification of results. It was found that splashing may be reduced by as much as 85% by controlling the air flow rate into the convertor  

    Geometry optimization of a fibrous scaffold based on mathematical modelling and CFD simulation of a dynamic cell culture

    , Article Computer Aided Chemical Engineering ; Volume 38 , 2016 , Pages 1413-1418 ; 15707946 (ISSN); 9780444634283 (ISBN) Tajsoleiman, T ; Abdekhodaie, M. J ; Gernaey, K. V ; Krühne, U ; Kravanja, Z ; Bogataj, M ; Sharif University of Technology
    Elsevier B.V  2016
    In tissue engineering, the development of a tissue essentially depends on supply of an adequate amount of nutrients and the design of a proper biophysical micro-environment for cells. The limitation of the available initial number of cells, expensive substances and time consuming experiments are the main bottlenecks in this type of processes. In this regard, mathematical modelling and computational fluid dynamics simulation (CFD) are powerful tools to identify an efficient and optimized design by providing reliable insights of the process. This study presents a mathematical model and CFD simulation of cartilage cell culture under a perfusion flow, which allows not only to characterize the... 

    Pressure-driven liquid-liquid separation in Y-shaped microfluidic junctions

    , Article Chemical Engineering Journal ; Volume 328 , 2017 , Pages 1075-1086 ; 13858947 (ISSN) Foroozan Jahromi, P ; Karimi Sabet, J ; Amini, Y ; Fadaei, H ; Sharif University of Technology
    On-chip phase separation of multiphase microflows at the divergence point of Y-shaped microfluidic junctions is an effective way for integrating continuous microstructured devices. In this study, flow pattern maps of various solvent pairs based on the volumetric flow rates of both phases have been drawn experimentally and compared with numerical prediction to investigate the effective domain for which complete phase separation occurred. Furthermore, sufficient separation of aqueous and organic phases at the end of the microchannel was achieved by controlling the pressure difference at the liquid-liquid interface via loading back-pressure on the organic phase. A mathematical model based on... 

    Hopf bifurcation of an age-structured virus infection model

    , Article Discrete and Continuous Dynamical Systems - Series B ; Volume 23, Issue 2 , March , 2018 , Pages 861-885 ; 15313492 (ISSN) Mohebbi, H ; Aminataei, A ; Browne, C. J ; Razvan, M. R ; Sharif University of Technology
    American Institute of Mathematical Sciences  2018
    In this paper, we introduce and analyze a mathematical model of a viral infection with explicit age-since infection structure for infected cells. We extend previous age-structured within-host virus models by including logistic growth of target cells and allowing for absorption of multiple virus particles by infected cells. The persistence of the virus is shown to depend on the basic reproduction number R0. In particular, when R0 ≤ 1, the infection free equilibrium is globally asymptotically stable, and conversely if R0 > 1, then the infection free equilibrium is unstable, the system is uniformly persistent and there exists a unique positive equilibrium. We show that our system undergoes a... 

    Mathematical modeling of dermal wound healing: A numerical solution

    , Article 2010 The 2nd International Conference on Computer and Automation Engineering, ICCAE 2010, 26 February 2010 through 28 February 2010, Singapore ; Volume 2 , 2010 , Pages 153-156 ; 9781424455850 (ISBN) Azizi, A ; Ghaemi Osgouie, K ; Sharif University of Technology
    Though wound healing process is well-researched, this area is poorly known. One reason is that all interactions have not been discovered, the main reason, though, is that the involved processes interact in a very complicated manner with nonlinear feedback. Such complex feedback mechanisms can be easily addressed by mathematical modeling. This paper contains a review of the mathematical modeling of cell interaction with extracellular matrix components during the process of dermal wound healing with focusing on remodeling phase. The models are of partial differential equation type and solved by numerical method  

    Dermal wound healing-remodeling phase: A biological review

    , Article 2010 The 2nd International Conference on Computer and Automation Engineering, ICCAE 2010, 26 February 2010 through 28 February 2010, Singapore ; Volume 2 , 2010 , Pages 88-90 ; 9781424455850 (ISBN) Azizi, A ; Ghaemi Osgouie, K ; Sharif University of Technology
    Though wound healing process is well-researched, this area is poorly known. One reason is that all interactions have not been discovered, the main reason, though, is that the involved processes interact in a very complicated manner with nonlinear feedback. Such complex feedback mechanisms can be easily addressed by mathematical modeling. This paper contains a review of the mathematical modeling of cell interaction with extracellular matrix components during the process of dermal wound healing with focusing on remodeling phase. The models are of partial differential equation type and solved by finite element method  

    Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

    , Article Chinese Journal of Chemical Engineering ; Volume 23, Issue 8 , August , 2015 , Pages 1316-1325 ; 10049541 (ISSN) Hasany, M ; Malakootikhah, M ; Rahmanian, V ; Yaghmaei, S ; Sharif University of Technology
    Chemical Industry Press  2015
    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogenation method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor... 

    An optimal approach for maximizing the number of adjacencies in multi floor layout problem

    , Article International Journal of Production Research ; Volume 53, Issue 11 , 2015 , Pages 3462-3474 ; 00207543 (ISSN) Neghabi, H ; Ghassemi Tari, F ; Sharif University of Technology
    Taylor and Francis Ltd  2015
    Multi-floor facility layout problem concerns the arrangement of departments on the different floors. In this paper, a new mathematical model is proposed for multi-floor layout with unequal department area. Maximising the number of useful adjacencies among departments is considered as the objective function. The adjacencies are divided into two major categories: horizontal and vertical adjacencies. The horizontal adjacency may be occurred between the departments assigned to same floors while the vertical can be happened between departments assigned to any consecutive floors. A minimum common boundary length (surface area) between any two horizontal (vertical) adjacent departments is... 

    Experimental and modeling study of catalytic reaction of glucose isomerization: Kinetics and packed-bed dynamic modeling

    , Article AIChE Journal ; Volume 54, Issue 5 , 2008 , Pages 1333-1343 ; 00011541 (ISSN) Molaei Dehkordi, A ; Safari, I ; Karima, M. M ; Sharif University of Technology
    The kinetics and equilibrium of isomerization reaction of D-glucose to D-fructose have been investigated using a commercial immobilized glucose isomer ase (IGI), Sweetzyme type IT®, in a batch stirred-tank reactor. The batch experimental data were used to model the reaction kinetics using the well-known Michaelis-Menten rate expression. The kinetic model was utilized in a dynamic-mathematical model for a packed-bed reactor to predict the concentration profiles of D-glucose and D-fructose within the reactor. The experimental results for the fractional conversion of D-glucose in the packed-bed reactor of IGI catalyst indicated that the model prediction of the transient and steady-state... 

    On the hardware-software partitioning: The Classic General Model (CGM)

    , Article 2006 Canadian Conference on Electrical and Computer Engineering, CCECE'06, Ottawa, ON, 7 May 2006 through 10 May 2006 ; 2006 , Pages 1922-1925 ; 08407789 (ISSN); 1424400384 (ISBN); 9781424400386 (ISBN) JavanHemmat, H ; Goudarzi, M ; Hessabi, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    In this paper we introduce a mathematical modeling tool (called Classic General Model: CGM) for the general problem of hardware-software codesign so that different partitioning algorithms can be easily and quickly developed and compared in this same framework. CGM introduces a simple but efficient model which supports single/multiprocessor, primal and dual approaches, fine or coarse granularity. CGM determines solutions by stating Mapping, Implementation and Permutation arrays. For judging among solutions of a certain algorithm, an Objective Function is defined. After modeling the problem by CGM we have a classic problem: finding the best values for elements of three arrays to optimize the... 

    Parallel machine scheduling problem with preemptive jobs and transportation delay

    , Article Computers and Operations Research ; Vol. 50, issue , Oct , 2014 , p. 14-23 Shams, H ; Salmasi, N ; Sharif University of Technology
    In this research the parallel machine scheduling problem with preemption by considering a constant transportation delay for migrated jobs and minimization of makespan as the criterion i.e., Pm|pmtn(delay)|Cmax is investigated. It is assumed that when a preempted job resumes on another machine, it is required a delay between the processing time of the job on these two machines. This delay is called transportation delay. We criticize an existing mathematical model for the research problem in the literature [Boudhar M, Haned A. Preemptive scheduling in the presence of transportation times. Computers & Operations Research 2009; 36(8):2387-93]. Then, we prove that there exists an optimal schedule... 

    Bayesian denoising framework of phonocardiogram based on a new dynamical model

    , Article IRBM ; Volume 34, Issue 3 , 2013 , Pages 214-225 ; 19590318 (ISSN) Almasi, A ; Shamsollahi, M. B ; Senhadji, L ; Sharif University of Technology
    In this paper, we introduce a model-based Bayesian denoising framework for phonocardiogram (PCG) signals. The denoising framework is founded on a new dynamical model for PCG, which is capable of generating realistic synthetic PCG signals. The introduced dynamical model is based on PCG morphology and is inspired by electrocardiogram (ECG) dynamical model proposed by McSharry et al. and can represent various morphologies of normal PCG signals. The extended Kalman smoother (EKS) is the Bayesian filter that is used in this study. In order to facilitate the adaptation of the denoising framework to each input PCG signal, the parameters are selected automatically from the input signal itself. This... 

    Dynamics of a running below-knee prosthesis compared to those of a normal subject

    , Article Journal of Solid Mechanics ; Volume 5, Issue 2 , 2013 , Pages 152-160 ; 20083505 (ISSN) Mamaghani, A. E ; Zohoor, H ; Firoozbakhsh, K ; Hosseini, R ; Sharif University of Technology
    Islamic Azad University  2013
    The normal human running has been simulated by two-dimensional biped model with 7 segments. Series of normal running experiments were performed and data of ground reaction forces measured by force plate was analyzed and was fitted to some Fourier series. The model is capable to simulate running for different ages and weights at different running speeds. A proportional derivative control algorithm was employed to grant stabilization during each running step. For calculation of control algorithm coefficients, an optimization method was used which minimized cinematic differences between normal running model and that of the experimentally obtained from running cycle data. This yielded the... 

    A fuzzy mathematical model for supplier selection and order allocation considering green vehicle routing problem

    , Article International Journal of Logistics Systems and Management ; Volume 27, Issue 2 , 2017 , Pages 151-163 ; 17427967 (ISSN) Ramezanzadeh Baraki, R ; Kianfar, F ; Sharif University of Technology
    Inderscience Enterprises Ltd  2017
    Recently, with the expansion of environmental issues and raising of customers' awareness, companies are experiencing huge pressure from shareholders and the government for greater compatibility with their environment. Companies and industry owners must implement green operations in their daily activities to be able to keep up with the competitive atmosphere of the environment. One of the most important operations to be implemented is cooperating with green suppliers. In this study, a multi-objective mathematical model is proposed to select suppliers and allocate optimal orders to them in a two-echelon supply chain, including supply and distribution echelons. The proposed model focuses on the... 

    Nonlinear power balance control of a SPA hydraulic hybrid truck

    , Article 2009 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM 2009, Singapore, 14 July 2009 through 17 July 2009 ; 2009 , Pages 805-810 ; 9781424428533 (ISBN) Taghavipour, A ; Alasty, A ; Saadat Foumani, M ; Sharif University of Technology
    An integrated procedure for mathematical modeling and power control balance for a SPA (Split Parallel Architecture) hydraulic hybrid vehicle is presented in this paper. Dynamic mathematical model of the powertrain is constructed firstly, which includes five modules: diesel engine, traction motor, starter, loading pump and accumulator. Based on the mathematic model of control modes a stability analysis is done. For some control modes a Sliding Mode Control is designed, which uses full-states closed-loop feedback. The paper finally illustrates and discusses the results of simulation. The results show that the performance and stability of control modes are proper and a power control strategy... 

    Robust control strategy for HBV treatment: Considering parametric and nonparametric uncertainties

    , Article Control Applications for Biomedical Engineering Systems ; 2020 , Pages 127-147 Aghajanzadeh, O ; Sharifi, M ; Falsafi, A ; Sharif University of Technology
    Elsevier Inc  2020
    Hepatitis is one of the most perilous viral infectious diseases and many people suffer from it all around the world. In particular, hepatitis B is a terribly dangerous disease which may cause severe liver damage or cancer if it is not treated. Recently, several dynamic models have been developed from experimental studies for describing such diseases mathematically. The certainty of these dynamics models is questionable in realistic treatment processes. Thus, the modeling uncertainties should be considered in the dynamics, which necessitates employing robust control strategies capable to overcome these uncertainties. Accordingly, in this research, a control strategy is developed in order to... 

    A theoretical and industrial study of component co-adsorption on 3A zeolite: an industrial case

    , Article Chemical Papers ; Volume 74, Issue 2 , August , 2020 , Pages 651-661 Jafari, L ; Moradi, H ; Tavan, Y ; Sharif University of Technology
    Springer  2020
    The 3A zeolite is an excellent adsorbent for natural gas dehydration due to low energy requirement in regeneration step and easy operation. To perform a reliable modeling, a good equilibrium adsorption isotherm is mandatory. Accordingly, water, methane, methyl mercaptan (M-mercaptan) and CO2 adsorption isotherms and also the competitive adsorption loading versus temperature are described for the system using molecular simulation and mathematical models. It is found that CO2 competes with water for adsorption on 3A and lower temperature is required for selective removal of water. The mathematical model results showed that M-mercaptan and CO2 quickly adsorb on 3A and capacity of 3A for water... 

    Modeling age hardening kinetics of an Al-Mg-Si-Cu aluminum alloy

    , Article Journal of Materials Processing Technology ; Volume 205, Issue 1-3 , 26 August , 2008 , Pages 388-393 ; 09240136 (ISSN) Eivani, A. R ; Karimi Taheri, A ; Sharif University of Technology
    In this paper, an Al-Mg-Si-Cu aluminum alloy was exposed to various heat treatment processes and the effect of precipitation hardening on hardness was investigated as a function of time and temperature. It was concluded that the variation in time and temperature can improve the hardness of the alloy. The work revealed that time and temperature play an important role in the precipitation hardening process of the alloy. To achieve the maximum hardness, an optimum aging cycle should be used which is heating at 180-190 °C for 15-18 h. Kinetics studies show an apparent activation energy of 58 kJ/mol. A relationship was derived which can be used to estimate the hardness at a given time and... 

    Designing and implementing two internet based exam systems using synchronous and asynchronous models

    , Article 2008 10th International Conference on Advanced Communication Technology, Phoenix Park, 17 February 2008 through 20 February 2008 ; Volume 3 , 2008 , Pages 2135-2139 ; 17389445 (ISSN); 9788955191356 (ISBN) Shirali Shahreza, M. H ; Shirali Shahreza, M ; Sharif University of Technology
    In this paper, two different systems for taking exams through the Internet are described and analyzed. They have been designed and executed in Yazd and Shahed Universities. These systems enable us to take the multiple-choice and descriptive exams. In these systems, the exam questions are prepared by the instructor of the concerned lesson and placed in the system database. The students who have taken that lesson can be connected to the system from wherever they want. After entering their username and password they can take part in the exam. One of these systems has been created on the basis of the synchronous model and another one has been developed on the basis of the asynchronous model.... 

    SimDiv: A new solution for protein comparison

    , Article Lecture Notes in Electrical Engineering ; Volume 6 , 2008 , Pages 467-483 ; 18761100 (ISSN); 9780387749341 (ISBN) Sayyadi, H ; Salehi, S ; Ghodsi, M ; Sharif University of Technology
    The number of known proteins is increasing every day; tens of thousands have been studied and categorized by now. In this chapter, we propose amodel for protein matching or extracting similar parts of two given proteins. We focus on the computational geometric approach and the graph matching method that are used to model and compare the sequence and 3D structure of proteins. The remainder ofthis chapter is organized as follows. We first have a glance at the related works. There are two major methods used in the literature: Delaunay tetrahedralization and similarity flooding.We explain the required information in the next section as background knowledge, and then propose a new idea in Sect....