Search for: deformable-modeling
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    Liver Segmentation in CT Images

    , M.Sc. Thesis Sharif University of Technology Babagholami Mohammadabadi, Behnam (Author) ; Manzouri, Mohammad Taghi (Supervisor)
    Image segmentation has a huge amount of applications in machine vision, target detection, medical image processing, etc. In many medical researches such as Organ and Gland Volume Specification, Analysis of Anatomical Structures and Multimodal Image Registration, Organ
    Segmentation is the first step of preprocessing.Since detection of diseases out of medical images depends on organ segmentation results,the segmentation process is done by experts which has a lot of disadvantages such as high time computation, high cost, etc. Hence, designing algorithms that can segment images with high accuracy and need minimum user interaction are desirable. So, in this thesis, a new
    knowledge based... 

    Investigation and Characterization of Circulating tumor Cells (CTCs) by the Microfluidics Systems

    , M.Sc. Thesis Sharif University of Technology Yari, Alireza (Author) ; Vossoughi, Manoucher (Supervisor) ; Alemzadeh, Iran (Supervisor) ; Shamloo, Amir (Supervisor)
    Cancer is the second leading cause of death among humans as one of the major human concerns. More than 500,000 people die of cancer each year in the United States alone. Cancer mortality is mainly due to cancer metastasis. Metastasis is the escape of cancer cells from a primary tumor, the circulation of cells in the circulatory system (CTSs), the penetration of/from vessel wall, and the formation of a secondary tumor. It is still not clear how the cells survive in the circulatory system, along with the mechanical pressures and stresses that exist in the body's capillary channals. In this study, a microcirculation model for circulating cells with barriers was designed and constructed by the... 

    Deformation modeling of an FGM plate under external force

    , Article Advanced Materials Research ; Sharif University of Technology , Volume 622 , 2013 , Pages 246-253 ; 10226680 (ISSN) ; 9783037855638 (ISBN) Mortazavi Moghaddam, A. R ; Ahmadian, M. T ; Sarkeshi, M ; Kheradpisheh, A ; Sharif University of Technology
    Deformation modeling of an infinite plate of functionally graded materials (FGMs) loaded by normal force to the plate surface is studied. The material properties of FGM plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The governing equations are based on stress-strain relation and the equilibrium force equation. Keeping generality, FGM plate has been assumed as a multilayer with linear material property in each layer while arbitrary exponential material property through the thickness. A plate made of Aluminum and Alumina is considered as an example to illustrate the effects of the... 

    A coupled stream function-finite element analysis for wire drawing processes

    , Article International Journal of Advanced Manufacturing Technology ; Volume 57, Issue 9-12 , 2011 , Pages 917-926 ; 02683768 (ISSN) Hosseinabadi, H. G ; Serajzadeh, S ; Sharif University of Technology
    A numerical approach has been developed based on the stream function technique and the finite element analysis to predict required power and temperature rise in wire drawing processes. An admissible velocity field is first proposed using a stream function and then power consumption in the wire drawing is optimized to achieve sensible and unique deformation geometry. In addition, the finite element method together with axi-symmetric Petrov-Galerkin algorithm is coupled with the deformation model to assess the temperature distribution in both the deforming wire and the die during the process. The work hardening effects are also considered in the model both in the deformation zone and on the... 

    Real-time simulation of the nonlinear visco-elastic deformations of soft tissues

    , Article International Journal of Computer Assisted Radiology and Surgery ; Volume 6, Issue 3 , 2011 , Pages 297-307 ; 18616410 (ISSN) Basafa, E ; Farahmand, F ; Sharif University of Technology
    Purpose: Mass-spring-damper (MSD) models are often used for real-time surgery simulation due to their fast response and fairly realistic deformation replication. An improved real time simulation model of soft tissue deformation due to a laparoscopic surgical indenter was developed and tested. Method: The mechanical realization of conventional MSD models was improved using nonlinear springs and nodal dampers, while their high computational efficiency was maintained using an adapted implicit integration algorithm. New practical algorithms for model parameter tuning, collision detection, and simulation were incorporated. Results: The model was able to replicate complex biological soft tissue... 

    Implementation of a constitutive model in finite element method for intense deformation

    , Article Materials and Design ; Volume 32, Issue 2 , February , 2011 , Pages 487-494 ; 02641275 (ISSN) Hosseini, E ; Kazeminezhad, M ; Sharif University of Technology
    Since the constitutive information is one of the most important aspects of material deformation analysis, here a new constitutive model is proposed that can investigate the behavior of material during intense deformation better than existent models. The model that is completely based on physical mechanisms can predict all stages of flow stress evolution and also can elucidate the effects of strain and strain rate on flow stress evolution of material during intense plastic deformation. Here as an application, implementation of the constitutive model in finite element method (FEM) is used to compare two methods of sever plastic deformation (SPD) processes of copper sheet; repetitive... 

    The kinetics of isothermal and non-isothermal recovery within cold-rolled aluminum alloy

    , Article Multidiscipline Modeling in Materials and Structures ; Volume 11, Issue 1 , 2015 , Pages 88-101 ; 15736105 (ISSN) Shabaniverki, S ; Serajzadeh, S ; Sharif University of Technology
    Emerald Group Publishing Ltd  2015
    Purpose - The purpose of this paper is to study the kinetics of static recovery in cold-rolled aluminum alloy under different heating rates. Design/methodology/approach - Deformation modeling was first performed to assess the distributions of plastic strain and stress within the deformed alloy. In the next stage, thermal analysis and the rate equation of static recovery were employed to determine the progress of static recovery under non-isothermal conditions. Accordingly, a thermal finite element analysis and the Runge-Kutta method were utilized to handle the transient heat conduction and the progress of static recovery. Finally, low temperature annealing heat treatments were conducted to... 

    On size-dependent nonlinear free vibration of carbon nanotube-reinforced beams based on the nonlocal elasticity theory: Perturbation technique

    , Article Mechanics Based Design of Structures and Machines ; 2020 Taati, E ; Borjalilou, V ; Fallah, F ; Ahmadian, M. T ; Sharif University of Technology
    Taylor and Francis Inc  2020
    Based on the first-order shear deformation (FSD) model and nonlocal elasticity theory, the simultaneous effects of shear and small scale on the nonlinear vibration behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams are investigated for the first time. To this end, the governing equations of bending and stretching with von Kármán geometric nonlinearity are decoupled into one fourth-order partial differential equation in terms of transverse deflection. A closed-form solution of the nonlinear natural frequency, which can be used in conceptual design and optimization algorithms of FG- CNTRC beams with different boundary conditions, is developed using a hybrid... 

    Comparison of mouse embryo deformation modeling under needle injection using analytical Jacobian, nonlinear least square and artificial neural network techniques

    , Article Scientia Iranica ; Volume 18, Issue 6 , 2011 , Pages 1486-1491 ; 10263098 (ISSN) Abbasi, A. A ; Ahmadian, M. T ; Vossoughi, G. R ; Sharif University of Technology
    Analytical Jacobian, nonlinear least square and three layer artificial neural network models are employed to predict deformation of mouse embryos under needle injection, based on experimental data captured from literature. The Maximum Absolute Error (MAE), coefficient of determination ( R2), Relative Error of Prediction (REP), Root Mean Square Error of Prediction (RMSEP), NashSutcliffe coefficient of efficiency ( Ef) and accuracy factor ( Af) are used as the basis for comparison of these three models. Analytical Jacobian, nonlinear least square and ANN models have yielded the correlation coefficient of 0.9985, 0.9964 and 0.9998, respectively. The REP between the models predicted values and...