Search for: three-dimensional-modeling
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    Axial-flow compressor performance prediction in design and off-design conditions through 1-D and 3-D modeling and experimental study

    , Article Journal of Applied Fluid Mechanics ; Volume 9, Issue 5 , 2016 , Pages 2149-2160 ; 17353572 (ISSN) Peyvan, A ; Hajilouy benisi, A ; Sharif University of Technology
    Isfahan University of Technology 
    In this study, the main objective is to develop a one dimensional model to predict design and off design performance of an operational axial flow compressor by considering the whole gas turbine assembly. The design and off-design performance of a single stage axial compressor are predicted through 1D and 3D modeling. In one dimensional model the mass, momentum and energy conservation equations and ideal gas equation of state are solved in mean line at three axial stations including rotor inlet, rotor outlet and stator outlet. The total to total efficiency and pressure ratio are forecasted using the compressor geometry, inlet stagnation temperature and stagnation pressure, the mass flow rate... 

    Modeling of Oxygen Transport and Exchange in an Acinus

    , M.Sc. Thesis Sharif University of Technology Mortazavi Ashkzari, Mohammad Sadegh (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    An acinus is defined as the complex of airways supplied by one first order respiratory or transitional bronchiole. In this part, the replenishment of oxygen at the alveolar surface occurs by a combination of convective air flow with diffusion of oxygen in the air. So for studying gas exchange in the lung, modeling gas species transport and exchange in an acinus is important. Due to lacking direct measurements of the distribution of oxygen (or carbon dioxide) concentration in the acinus, several mathematical models have been developed and studied by numerical simulations. But in none of them the influence of breathing pattern and the role of blood flow in restricting the gas exchange rate have... 

    Nonlinear seismic assessment of steel moment frames under bidirectional loading via endurance time method

    , Article Structural Design of Tall and Special Buildings ; Vol. 23, issue. 6 , April , 2014 , p. 442-462 ; ISSN: 15417794 Valamanesh, V ; Estekanchi, H. E ; Sharif University of Technology
    In this paper, considering horizontal components of seismic excitation, an algorithm for the nonlinear multi-component analysis of building structures by the Endurance Time (ET) method is proposed, and results of the ET method for various steel moment frames with one to seven stories are verified by comparing with the results from Nonlinear Time History Analysis with use of two different sets of ground motions. In addition, several parameters such as eccentricities and irregularities in structure, rotational and lateral stiffness, effect of hysteresis type and ductility have been considered for sensitivity analysis on results, obtained by ET method. Results show that on the basis of... 

    3D steady state seepage analysis of embankment dams

    , Article Electronic Journal of Geotechnical Engineering ; Volume 10 F , 2005 ; 10893032 (ISSN) Soleimanbeigi, A ; Jafarzadeh, F ; Sharif University of Technology
    Steady state seepage analysis of embankment dams is one of the most significant stages in the designing process. Currently, most seepage modeling of embankment dams is performed in two dimensions, often for the highest section, which include several simplifications. In this way, the effect of watertight elements such as grouting curtains in side abutments as well as their material properties is not taken into account in seepage analysis results. Especially if the dam is located in a narrow valley or the effect of existing faults beneath the dam is to be investigated, the results of the two-dimensional seepage analysis differ from those of three-dimensional (3D). In this paper, the... 

    Urine concentrating mechanism modelling in rat kidney inner medulla

    , Article 2016 23rd Iranian Conference on Biomedical Engineering and 2016 1st International Iranian Conference on Biomedical Engineering, ICBME 2016, 23 November 2016 through 25 November 2016 ; 2017 , Pages 111-116 ; 9781509034529 (ISBN) Sanatkhani, S ; Saidi, M. S ; Banazadeh, M. H ; Sharif University of Technology
    Physicians use charts that are prepared by experiments on animals or humans to prescribe drug dosage for patients. This method requires some precious amount of time by the Ministry of Health to approve new drugs to be used in healthcare centers. Three-dimensional modeling of the inner medulla by considering the known physiological features help us to predict the distribution of a drug or any minerals in the kidney. In this study we present modeling of the important species distribution including Na+ and urea in the rat inner medulla that influence the urine concentrating mechanism. We use a C++ code to develop the inner medulla geometry based on physiological data to better capture the... 

    A quasi-three-dimensional thermal model for multi-stream plate fin heat exchangers

    , Article Applied Thermal Engineering ; Volume 157 , 2019 ; 13594311 (ISSN) Niroomand, R ; Saidi, M. H ; Hannani, S. K ; Sharif University of Technology
    Elsevier Ltd  2019
    In this study, a novel pseudo-three-dimensional model is developed to find out both fluid and solid temperature distributions in multi-stream plate fin heat exchangers. In this simulation algorithm, heat exchangers can be in either parallel flow or cross flow configuration. The model considerations include: heat leakage of cap plates and side plates, conduction throughout the solid matrix of the heat exchanger, variable physical properties, and inlet mass flow rate maldistribution. Using the computational code, the effects of different factors such as: the number of layers, mass flow variation, inlet mass flow rate maldistribution, and stacking pattern on the thermal performance of the heat... 

    Verification of Two and Three Dimensional Seepage Analyses Results’ Correctness in Embankment Dams According to Instrumenting Data (Case Study: ZAGROS, SHIAN & HAALEH Dams)

    , M.Sc. Thesis Sharif University of Technology Yarahmadi, Nazanin (Author) ; Jafarzadeh, Fardin (Supervisor)
    Since, seepage- related problems account for more than forty percents of earth dams’ failure, seepage analysis is one of the most important stages in designing of embankment dams. The most usual method of making a seepage analysis is doing a two dimensional one in the maximum cross- section and generalizing its results to the third dimension. As a natural consequence of this kind of seepage analysis, the effect of valley shape and material properties’ changes along the third dimension are ignored and so, in narrow valleys where the cross-section changes along longitude profile or in the specific cases of nonhomogeneity, using this kind of analysis can make false results. Besides, because of... 

    Solidification of Fluid Inside the Pipeline to Fix or Replace the Defective Component

    , M.Sc. Thesis Sharif University of Technology Taheri, Mohammad Ali (Author) ; Saeedi, Mohammad Hassan (Supervisor)
    Pipe freezing has become well established in industry as a method of short-termisolation in order to carry out maintenance or repairs. It is often necessary to repair system components without plant shutdown or drainage of system having many piping structures which may have hazardous or expensive fluid. Therefore, a series of tests has been arranged to investigate the ice plug formation in two standard pipes with different diameter size. The freeze zone on the pipe has been created by means of an aluminum jacket which liquid nitrogen flows in it. In the tests the freezing time, amount of liquid nitrogen usage andthe pressure tolerance of ice plug have been determined. Moreover, the numerical... 

    Fuzzy-Pade' Method for Approximating the Aerodynamic Forces in Dynamic Modeling of the Flexible Flapping Wing

    , Ph.D. Dissertation Sharif University of Technology Abedinnasab, Mohammad Hossein (Author) ; Zohoor, Hassan (Supervisor)
    In this thesis, we have derived the exact equations of motion for flexible beams. The derived equations are compared with similar equations reported in the literature, and they demonstrate significant power in prediction of the numerical results. The model for planar beams is verified by the performed experiments on carbon fiber rods. A new highly convergent, efficient technique which is quite fast is also developed for both approximating and controlling a system, entitled as fuzzy-Pade method. We then have studied effects of the wing flexibility on enhancing the lift and trust coefficients in the flapping flight. Aerodynamic force generation due to flapping is simulated for both the... 

    Turn-to-Turn Fault Detection in Power Transformers in the Presence of Inrush Current

    , M.Sc. Thesis Sharif University of Technology Fallah Mollamahmod, Mahdi (Author) ; Hajipour, Ehsan (Supervisor)
    One of the most critical equipments in power grids are power transformers, which are vulnerable to damage due to the possibility of faults in its various components. A very common category of such faults is turn-to-turn fault in its winding. This fault initiates by the aging of the winding insulation with a short circuit of several adjacent loops to each other and if it is not detected quickly by the transformer protection, it will spread rapidly and can lead to irreparable failure in the transformer. Traditionally, turn-to-turn fault should be detected by mechanical pressure relays, however, due to the poor performance of these relays in the rapid detection of this type of fault, in the... 

    Three dimensional modeling of axonal microtubules

    , Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014, 26 November 2014 through 28 November 2014 ; November , 2014 , Pages 298-302 ; 9781479974177 (ISBN) Manuchehrfar, F ; Shamloo, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2014
    Axon is a filament in neuronal system and axonal microtubules are bundles in axons. In axons, microtubules are coated with microtubule-associated protein tau, a natively unfolded profuse filamentous protein in the central nervous system. These proteins are responsible for the cross-linked structure of the axonal microtubule bundles. Through complimentary dimerization with other tau proteins, bridges are formed to nearby microtubules to create bundles. The transverse reinforcement of microtubules by cross-linking to the cytoskeleton has been shown to enhance their ability to bear compressive loads. Though microtubules are conventionally regarded as bearing compressive loads, in certain... 

    A three-dimensional constitutive model for magnetic shape memory alloys under magneto-mechanical loadings

    , Article Smart Materials and Structures ; Volume 26, Issue 1 , 2017 ; 09641726 (ISSN) Mousavi, M. R ; Arghavani, J ; Sharif University of Technology
    Institute of Physics Publishing  2017
    This paper presents a three-dimensional phenomenological constitutive model for magnetic shape memory alloys (MSMAs), developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold for variant reorientation is introduced which improves the model accuracy. Preassumed kinetic equations for magnetic domain volume fractions, decoupled equations for magnetization unit vectors and appropriate presentation of the limit function for martensite variant reorientation lead to a simple... 

    Three-dimensional modeling of density current in a straight channel

    , Article Journal of Hydraulic Engineering ; Volume 135, Issue 5 , 2009 , Pages 393-402 ; 07339429 (ISSN) Firoozabadi, B ; Afshin, H ; Aram, E ; Sharif University of Technology
    Dense underflows are continuous currents that move downslope due to their density being heavier than that of the ambient water. In this work, a steady density current with a uniform velocity and concentration from a narrow sluice gate enters into a wide channel of lighter ambient fluid and moves forward downslope. Experiments varying inlet velocity and concentration and hence inlet Richardson numbers were conducted. Numerical simulations were also performed with a low-Reynolds number k-ε model. The results of numerical simulation agree well with the experimental data. © 2009 ASCE  

    Numerical study to evaluate the important parameters affecting the hydrodynamic performance of manta ray's in flapping motion

    , Article Applied Ocean Research ; Volume 109 , 2021 ; 01411187 (ISSN) Safari, H ; Abbaspour, M ; Darbandi, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Manta ray swimming or bio-inspiration propulsion system, as a special type of marine propulsion system, is used for submersible vehicles that require high-speed maneuverability and stability, such as glider and AUV. In a manta ray swimming, the thrust force is generated by a couple of undulation and oscillation of wing, so that the direction of undulation wave and oscillation is upright and perpendicular to the direction of thrust force, respectively. It is possible to combine these two movement modes (flapping motion) on the three-dimensional model without considering the effects of wing twisting and flexibility to simplify and better understand the physical behaviors or special study of... 

    Evaluation of the Performance of Fluid Dampers in Controlling the Seismic-Induced Response of Structures

    , M.Sc. Thesis Sharif University of Technology Jahromi Shirazi, Mohammad Mahdi (Author) ; Rahimzadeh Rofooei, Fayaz (Supervisor)
    Natural disasters, such as earthquakes and hurricanes, can strike without warning, resulting in a range of destruction from structural damage to loss of life. For this reason, research on structural control, which provides a new basis for design of structural systems against winds, earthquakes, waves, and traffic loadings, become of interest in civil engineering. This thesis focuses on using fluid dampers as a passive energy dissipation device. Viscous Fluid Dampers (VFD) are the most commonly used passive energy dissipation devices that are manufactured in various forms. However, the orifice type of Viscous Fluid Damper (VFD) is considered for structural applications. In this thesis, the... 

    3D Modeling of Soccer Players from an Arbitrary Viewpoint Using Multi-view video images

    , M.Sc. Thesis Sharif University of Technology JebalBarezi Sarbijan, Elham (Author) ; Kasaei, Shohreh (Supervisor)
    For penalty detection and interpretation of sport match scenes (such as soccer), it is sometimes necessary to watch the scene from an arbitrary viewpoint captured by a virtual camera. In this research, we focus on 3D reconstruction of soccer players using videos that are captured from relatively far distance to the soccer field. In capturing videos from sport scenes, such as soccer scenes, an important issue is the problem of capturing videos from a wide environment to cover almost all parts of the field. Using many cameras with overlapped views might be an answer to this problem but it is impractical due to its cost for capturing and transmitting the data. Furthrmore, because of capturing... 

    3D Reconstruction of Football Player Using Multi-view Videos

    , M.Sc. Thesis Sharif University of Technology Karami, Mansoureh (Author) ; Kasaei, Shohreh (Supervisor)
    One major problem in sport match analysis and interpretation is that there are restricted viewpoints of the game. 3D reconstruction allows us to have virtual replay from any viewpoint so that the events such as penalties can be detected easily. For achieving this purpose, we use many cameras with overlapped views that cover almost all parts of the field. After some preprocessing, 3D reconstruction and texture mapping, we can enhance the viewer experience by having arbitrary viewpoint of the match. In this research, we use two different visual hull methods for 3D reconstruction. In the first method, the visual hull of an object is computed efficiently and robustly from image contours. This... 

    Control of Experimental Swarm Robots for Identification, Imaging & 3D Modeling Purposes

    , M.Sc. Thesis Sharif University of Technology Moeini, Mohammad (Author) ; Alasty, Aria (Supervisor)
    The aim of this project is decentralized control of a group of robots (swarm robots); such that the aggregation maneuver, leader following, Identification and imaging the target, will be performed so good as to make a three-dimensional model of the target from these images. Swarm robots consist of a number of similar and limited features robots which interaction in a group of robots, will lead to special features for the group. Any agent of group decides what to do only with its local information from the environment. Swarm robots are more applicable for the jobs in which a distributed perception from the environments needed, for example space exploration and military operations.In this... 

    Experimental and Theoretical Investigation on Losses and Modeling Axial Flow Turbine

    , M.Sc. Thesis Sharif University of Technology Hashemi, Ahmad (Author) ; Hajilouy-Benisi, Ali (Supervisor)
    Prediction of axial flow turbine’s performance with different operating conditions due to the high costs and lack of reliable empirical data is always under developing. In this type of turbine, fluid flow is three-dimensional, viscous and highly turbulent. Nowadays, although a relatively detailed picture of the flow field can be obtained by the computational and numerical tools, but using of appropriate loss models in one-dimensional modeling for the performance prediction as well as optimization of the turbine in initial design phases, is a common trend.
    In the current study, aerodynamic losses in the axial flow turbine are investigated. Several loss models for the axial flow turbines... 

    Exact Solution for Electrical Impedance Tomography using DSP

    , M.Sc. Thesis Sharif University of Technology Soltani, Farnoosh (Author) ; Vosoughi Vahdat, Bijan (Supervisor)
    There are some problems in calculation of heavy and huge equations which are ill-posed and nonlinear. They need to be solved by the processors. The errors are important in our measurements because this precision is very important in calculation. The Block Method approach solving Forward Problem in Electrical Impedance Tomography (EIT) results produce an exact solution only if the measurements are done with enough accuracy. In this thesis, a 3D model of EIT with Block Method is implemented by means of Digital Signal Processor (DSP) to obtain exact results. In this work it has used a powerful processor called TMS320C6416DSK to reduce the measurement error in equations. It has used Code...