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Total 116 records

    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)
    Abstract
    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... 

    Exact Solution for Electrical Impedance Tomography using DSP

    , M.Sc. Thesis Sharif University of Technology Soltani, Farnoosh (Author) ; Vosoughi Vahdat, Bijan (Supervisor)
    Abstract
    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... 

    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)
    Abstract
    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... 

    Three Dimensional Computational Modeling of Multiphase Flow in Proton Exchange Membrane Fuel Cells

    , M.Sc. Thesis Sharif University of Technology Arbabi, Faraz (Author) ; Mazaheri, Karim (Supervisor) ; Roshandel, Ramin (Supervisor)
    Abstract
    Proton exchange membrane (PEM) fuel cell performance is directly related to the flow channel design on bipolar plates. Power gains can be found by varying the type, size, or arrangement of channels. It has been understood that the flow field design has deterministic role on mass transport and water management in a PEM Fuel cell. This study concentrates on improvements in the fuel cell performance through optimization of channel dimensions and configurations. A 3D, multi-component numerical model of flow distribution based on the Navier-Stokes equations using individual computer code is presented. The simulation results showed excellent agreement with the experimental results in previous... 

    FEM Analysis of the Effects of Geometric Parameters on the Superplastic Forming of Metal Matrix Composit

    , M.Sc. Thesis Sharif University of Technology Tehrani, Mehdi (Author) ; Abedian, Ali (Supervisor)
    Abstract
    In aerospace applications, the weight of structures is considered as a major performance parameter. One of the most effective ways for weight reduction is then attributed to the structurally continuous manufacturing of mechanical components. In this way, not only the weight, but also the stress concentration, the cost, joints and fasteners applications, and the time of manufacturing are noticeably reduced. With this method, components with complicated shapes could be formed in a single manufacturing step. Special specification of whisker reinforced Metal Matrix Composites (MMC’s) has made these materials very attractive for the aerospace applications.That is why the superplastic forming of... 

    3D Reconstruction of Football Player Using Multi-view Videos

    , M.Sc. Thesis Sharif University of Technology Karami, Mansoureh (Author) ; Kasaei, Shohreh (Supervisor)
    Abstract
    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... 

    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)
    Abstract
    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... 

    Evaluating the Resilience of the Transportation Network Against Extreme Flooding: A Case Study of Transportation Network of Shiraz City

    , M.Sc. Thesis Sharif University of Technology Zamani, Hassan (Author) ; Kermanshah, Amir Hassan (Supervisor)
    Abstract
    Because of severe weather events (such as floods and storms), transportation infrastructures are directly and indirectly damaged, which may cause many undesirable economic and social losses for people and cities. Among various severe events, flood is known as an important factor in the breakdown (closure of roads and bridges) of the components of the transportation network. Evaluating the performance of the city's road transport network against flood events leads to a better understanding of the network's condition and allows decision-makers to identify the weaknesses in the system and reduce potential damages as much as possible. In this research, with the aim of investigating the... 

    Investigating the Behavior of 3D Irregular Steel Structures with Seismic Base Isolation under Multi-Directional Excitations and Predicting Results by Using the Endurance Time Method

    , M.Sc. Thesis Sharif University of Technology Zarbilinezhad, Milad (Author) ; Esmail Pourestekanchi, Homayoon (Supervisor)
    Abstract
    This research has been performed with the aim of gaining familiarity with various types of seismic isolation systems, their unique features and numerous advantages, factors affecting their performance and finally their modelling and design. Despite the advantages of seismic isolation systems as control instruments, but where there is not enough information on the involved parameters in the performance of these systems, there is possibility of unpredictable behavior of the structures. Hence, considering the extent and influence of each parameter involved in the performance of the isolators, a parametric study is performed utilizing the 3D models under multi-directional excitations, using the... 

    Study the Effect of Staged Construction and Behavior of Concave Corner of Excavation Stabilized by Soldier Piles with Pretensioned Anchor by 3D Numerical Modeling

    , M.Sc. Thesis Sharif University of Technology Mehdizadeh, Mehdi (Author) ; Ahmadi, Mohammad Mehdi (Supervisor)
    Abstract
    In recent years, due to the development of cities and population growth, the number of underground floors and the depth of excavations have increased. Sustainability of excavation and control of deformation due to excavation process has always been considered as one of the important issues in geotechnical engineering. One of the most commonly used systems for deep excavation, especially in urban areas, is the soldier pile wall with tiebacks. This system consists of anchoring on soldier piles that are performed at horizontal distances around the excavation range. The cables have two parts. Unbond and bond length that, when pretensioned, have the task of transfering load out of the wedge of... 

    Analysis of Stability and Ground Settlement in Construction Stages of Underground Exchange Station between Line 3 and 4 At Mashhad Subway

    , M.Sc. Thesis Sharif University of Technology Lamei, Amin (Author) ; Sadaghiani, Mohammad Hossein (Supervisor)
    Abstract
    Deformation and Settlement of the ground surface and stability of large underground space is the main concern in the excavation under urban area. In order to control settlement and increase stability, it is necessary to use pre-Supporting system prior to excavation. Concrete Arc Pre-supporting System (CAPS) is one of the most useful pre-supporting methods which is used in exchange station of line 3 and 4 of Mashhad subway. Line 3 and 4 are parallel in Shohada square and the groundwater level is above the whole station structure. To analyze deformation of the ground due to excavation stages, the station was modeled in 2D and 3D by Abaqus. In this study, to estimate ground Deformation, we need... 

    The Behavior of Supporting Structures with Pretension Anchors by Geotechnical Softwares

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Alireza (Author) ; Ahmadi, Mohammad Mehdi (Supervisor)
    Abstract
    In recent years, due to urban expansion and population growth, number of floors and excavations depth has increased. Stabilization of excavations is one of the most important issues in geotechnical engineering. Today, one of the most widely used methods that is used in deep excavations is brace soil by steels and pretension them. In this thesis tries to evaluate static behavior of flexible supporting structures with pretension anchors by using PLAXIS2D, FLAC3D and GEOSTUDIO softwares. The objective of this modeling is better understanding the static behavior of walls, comparing the two and three dimensional modeling and the effect of corners of excavation on deformation. The results shows... 

    Study of the Interaction of Non-level Crossing Tunnels, Case Study of Crossing of Tunnels of Line 1 and Line 7 of Tehran Metro

    , M.Sc. Thesis Sharif University of Technology Pourjavadi, Sobhan (Author) ; Sadaghiani, Mohammad Hosein (Supervisor)
    Abstract
    As the crowded cities require public transportation and because of lack of space on the ground, Subway and boring underground tunnels encountered. In this thesis the interaction of boring the line 7 of Tehran metro with the existing station of line 1 of Tehran metro (Molavi station) is studied. By changing the soil specification, The surface settlement is significant so the soil specification is one of the important parameters of the interaction. For comparinf the effect of these parameters, the soil settlement and bending moments is investigated in different parts of station while the lower tunnel is passing beneath it. The 3D Abaqus software is used for modeling this interaction. In... 

    Evaluation the Surface Settlement and Interaction Between Tunnelinline2 and Metro Station Inline1 of Mashhad Metro at Intersection Using 3-D Numerical Modeling

    , M.Sc. Thesis Sharif University of Technology Ghasempour, Hamid (Author) ; Sadaghiani, Mohammad Hossein (Supervisor)
    Abstract
    In this study, the interaction of tunneling of line 2 of Mashhad metro and existing metro station (Shariati station) in line 1 has been investigated. To produce the stress and displacement which is caused by excavation of station, the process of station excavation has been modeled by method of cut and cover.This method is the common method for station construction at Shallow depth and is used in several cases in line 1 of Mashhad metro. The piled-raft system is used in foundation of central part of the station to reduce the settlements and the effects of interactions between the station and new tunnel. The new tunnel under the station is surrounded by two rows of lateral piles with distance... 

    Evaluation of Endurance Time Method in Nonlinear Dynamic Analysis of Unreinforced Brick Masonry Buildings

    , M.Sc. Thesis Sharif University of Technology Kiani Nia, Mohammad Ali (Author) ; Esmaeil Pourestekanchi, Homayoon (Supervisor)
    Abstract
    The existing statistical studies implies that in Iran like most of developing countries, the great percent of houses are traditional. Statistics of the most disastrous current quakes also show damages caused by masonry structures in developing countries. The main problem of brick and masonry structures especially the unreinforced one is their weak performance against quake. Different methods are use to analyse the seismic performance of this structures. The modern endurance time method is a kind of time history analysis using standard increasing accelerograms which examines different parameters of structure behavior during excitation actions. In this project we analyse these structures using... 

    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)
    Abstract
    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... 

    Parametric Analysis of Interaction Between Crossing Tunnels at Different Level

    , M.Sc. Thesis Sharif University of Technology Tohidi, Amin (Author) ; Sadagiani, Mohammad Hossein (Supervisor)
    Abstract
    Sensibility of parameters that influence the Interaction between crossing tunnel at different level such as Soil charactristic, Construction procedure,Method of excavation,Rigidity of lining,Distance between tunnels and angle of intersection is studied. For comparison above parameters the surface settlement and bending moment during the excavation is measured .In order to simulate the Interaction between Crossing tunnels, use 3D finite element model with Abaqus program. The soil govern elasto-plastic mohr-coloumb constitutive equation.Parametric Analysis shows the great and different influence of each parameter that we can able to minimize this interaction with correct choose of this... 

    Study of the Effect of Central Beam Column (CBC) Structure on Sequential Excavation of Large Span Underground Station

    , M.Sc. Thesis Sharif University of Technology Valizade Givi, Amir (Author) ; Ahmadi, Mohammad Mehdi (Supervisor)
    Abstract
    Effect of utilizing Central Beam Column (CBC) structure on shallow, large span underground spaces excavation is studied. The CBC method focuses on increasing the overall rigidity of tunnel supporting system prior to full face excavation, in which central drift excavation is limited to the dimensions of the central beam and column to reduce disturbances. Constructing the central beam and column structure, the excavation is completed with NATM excavation method in a symmetric manner about centerline. In CBC method on each side of the centerline there is an arch structure composed of the initial lining resting on roof beam on top and bottom beam at the invert. The roof and bottom beams take the... 

    Modeling of a Turbocharger Turbine to Predict Its Performance and Investigating the Possibility of Improvement using Experimental Results

    , M.Sc. Thesis Sharif University of Technology Meary, Mohammad Hosein (Author) ; Hajilouy Benisi, Ali (Supervisor)
    Abstract
    Radial inflow gas turbines are widely used in auxiliary power units, small industrial gas turbines and turbocharger of internal combustion engines. They have advantage for low mass flow rate and wide range operation conditions. This research aimed to improve aerodynamic performance of the radial turbine of GT4082 Garret turbocharger. First, performance characteristics of the turbine were obtained experimentally at Turbocharger Laboratory of Sharif University of Technology. Laboratory results are the basis for modeling evaluation. Then, a one-dimensional model was developed to predict the turbine performance characteristics. The model results were compared with experimental results, that... 

    Investigation of Excitation-contraction behavior in Skeletal Muscle by Means of Chemomechanical Modeling

    , Ph.D. Dissertation Sharif University of Technology Karami, Mina (Author) ; Zohoor, Hassan (Supervisor) ; Firoozbakhsh, Keikhosrow (Supervisor)
    Abstract
    Numerous studies have shown a direct relationship between skeletal muscle active force and intracellular calcium ion concentrations; In fact, no matter how the muscle is stimulated (neurological, electrical, chemical, and mechanical stimuli), the main cause of muscle activation and consequently force generation is calcium ions.According to this scientific finding, the purpose of this study is to present a new chemo-mechanical multiscale model of skeletal muscle based on the fundamental principles of continuum thermodynamics. In this model, unlike other similar studies, muscle active force is not considered as the conventional multiplication of isometric force in a set of corrective...