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    Finite element analysis of miniscrew placement in mandibular alveolar bone with varied angulations

    , Article European Journal of Orthodontics ; Volume 37, Issue 1 , August , 2015 , Pages 56-59 ; 01415387 (ISSN) Perillo, L ; Jamilian, A ; Shafieyoon, A ; Karimi, H ; Cozzani, M ; Sharif University of Technology
    Oxford University Press  2015
    Summary Background: Titanium miniscrews are increasingly used as orthodontic anchorage. Various factors are known to affect the stability of miniscrew. Placement angle is one of the most controversial issues in this area. Thus, the aim of this finite element study was to evaluate the influence of placement angle and direction of force on the stability of miniscrews. Materials and methods: Finite element analysis was performed using miniscrews inserted into 1mm of cortical bone and 10mm of trabecular bone at angles of 30, 60, 90, 120, and 150 degrees to the alveolar bone. Force of 2 Newton (N) was applied to the heads of the miniscrews in two directions of 0 and 30 degrees. Results: The... 

    A lagged implicit segregated data reconstruction procedure to treat open boundaries

    , Article Journal of Computational Physics ; Volume 229, Issue 14 , July , 2010 , Pages 5418-5431 ; 00219991 (ISSN) Sani, M ; Saidi, M. S ; Sharif University of Technology
    The problem of treating open boundaries is still a challenging one. Applying fully developed condition is constrained to long enough domains. Without having enough physical evidence about what happens on boundaries, the domain extent could not be shortened and computational costs could not be reduced. From the advent of free (open) boundary conditions, they were confined to mixed finite element procedures. Recent works have extended their application to coupled finite volume solvers based on the shape function data reconstruction. A wider class of flow solvers available, however, rely on the segregated procedure where the velocity components and pressure are solved in succession. Moreover,... 

    How to set up stochastic equations for real world processes: markov–einstein time scale

    , Article Understanding Complex Systems ; 2019 , Pages 165-179 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    In Chaps. 16 – 21 we address a central question in the field of complex systems: Given a fluctuating (in time or space), sequentially uni- or multi-variant measured set of experimental data (even noisy data), how should one analyse the data non-parametrically, assess their underlying trends, discover the characteristics of the fluctuations, including diffusion and jump parts, and construct stochastic evolution equation for the data? © 2019, Springer Nature Switzerland AG  

    How to set up stochastic equations for real world processes: Markov–einstein time scale

    , Article Understanding Complex Systems ; 2019 , Pages 165-179 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    In Chaps. 16 – 21 we address a central question in the field of complex systems: Given a fluctuating (in time or space), sequentially uni- or multi-variant measured set of experimental data (even noisy data), how should one analyse the data non-parametrically, assess their underlying trends, discover the characteristics of the fluctuations, including diffusion and jump parts, and construct stochastic evolution equation for the data? © 2019, Springer Nature Switzerland AG  

    Comparing the stability regions for fractional-order PI controllers and their integer-order approximations

    , Article Proceedings of the IEEE Conference on Decision and Control, 15 December 2010 through 17 December 2010, Atlanta, GA ; 2010 , Pages 720-725 ; 01912216 (ISSN) ; 9781424477456 (ISBN) Rahimian, M. A ; Tavazoei, M. S ; Sharif University of Technology
    This paper proposes a scheme for computing the stable regions from which the parameters of a fractional-order PI controller can be selected. In particular, we extend a previously investigated method for plotting the stability regions of PIλ controllers to their integer-order approximations. Next we compare the two stability regions and derive their overlapping sections, which is referred to as the implementable stability region. In order for the final closed-loop system to be stable, the designer must choose the controller parameters from the overlapping section of the two stability regions. The devised scheme we believe can facilitate the design procedure for fractional-order PI... 

    A comprehensive multimodality heart motion prediction algorithm for robotic-assisted beating heart surgery

    , Article International Journal of Medical Robotics and Computer Assisted Surgery ; Volume 15, Issue 2 , 2019 ; 14785951 (ISSN) Mansouri, S ; Farahmand, F ; Vossoughi, G ; Alizadeh Ghavidel, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2019
    Background: An essential requirement for performing robotic-assisted surgery on a freely beating heart is a prediction algorithm that can estimate the future heart trajectory. Method: Heart motion, respiratory volume (RV) and electrocardiogram (ECG) signal were measured from two dogs during thoracotomy surgery. A comprehensive multimodality prediction algorithm was developed based on the multivariate autoregressive model to incorporate the heart trajectory and cardiorespiratory data with multiple inherent measurement rates explicitly. Results: Experimental results indicated strong relationships between the dominant frequencies of heart motion with RV and ECG. The prediction algorithm... 

    A recursive approach for analysis of snake robots using Kane's equations

    , Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 7 B , 2005 , Pages 855-861 ; 0791847446 (ISBN) Tavakoli Nia, H ; Pishkenari, H. N ; Meghdari, A ; Sharif University of Technology
    This paper presents a recursive approach for solving kinematic and dynamic problem in snake-like robots using Kane's equations. An n-link model with n-nonholonomic constraints is used as the snake robot model in our analysis. The proposed algorithm which is used to derive kinematic and dynamic equations recursively enhances the computational efficiency of our analysis. Using this method we can determine the number of additions and multiplications as a function of n. The proposed method is compared with the Lagrange and Newton-Euler's method in three different aspects: Number of operations, CPU time and error in the computational procedures. Copyright © 2005 by ASME  

    A finite volume central differencing scheme for simulation of the shut down procedure of a hydraulic system

    , Article International Journal of Fluid Power ; Volume 3, Issue 2 , 2002 , Pages 17-27 ; 14399776 (ISSN) Mazaheri, K ; Farahani, R. H ; Sharif University of Technology
    A new central differencing finite volume scheme is investigated for solution of unsteady hydraulic problems as water hammer in pipe systems. Special time stepping procedure similar to Runge-Kutta algorithm is used to stabilize this second order scheme. It is monotonized by adding dissipative terms including second and fourth derivatives of the conserved variables, with coefficients proportional to derivatives of pressure or volumetric flow, which keeps the second order of accuracy in smooth flow regions. The one-dimensional unsteady incompressible equations are solved for a water hammer situation, and results are compared to existing analytical solutions. Results are also compared with... 

    A computational modelling study of excitation of neuronal cells with triboelectric nanogenerators

    , Article Scientific Reports ; Volume 12, Issue 1 , 2022 ; 20452322 (ISSN) Nazari Vanani, R ; Mohammadpour, R ; Asadian, E ; Rafii-Tabar, H ; Sasanpour, P ; Sharif University of Technology
    Nature Research  2022
    Neurological disorders and nerve injuries, such as spinal cord injury, stroke, and multiple sclerosis can result in the loss of muscle function. Electrical stimulation of the neuronal cells is the currently available clinical treatment in this regard. As an effective energy harvester, the triboelectric nanogenerators (TENG) can be used for self-powered neural/muscle stimulations because the output of the TENG provides stimulation pulses for nerves. In the present study, using a computational modelling approach, the effect of surface micropatterns on the electric field distribution, induced voltage and capacitance of the TENG structures have been investigated. By incorporating the effect of... 

    Review on different experimental techniques developed for recording force-deformation behaviour of soft tissues; with a view to surgery simulation applications

    , Article Journal of Medical Engineering and Technology ; Volume 41, Issue 4 , 2017 , Pages 257-274 ; 03091902 (ISSN) Afshari, E ; Rostami, M ; Farahmand, F ; Sharif University of Technology
    Different experimental techniques which have been developed to obtain data related to force-deformation behaviour of soft tissues play an important role in realistically simulating surgery processes as well as medical diagnoses and minimally invasive procedures. Indeed, an adequate quantitative description of soft-tissue-mechanical-behaviour requires high-quality experimental data to be obtained and analysed. In this review article we will first scan the motivations and basic technical issues on surgery simulation. Then, we will concentrate on different experimental techniques developed for recording force-deformation (stress-strain) behaviour of soft tissues with focussing on the in-vivo... 

    Label-free electrochemical microfluidic biosensors: futuristic point-of-care analytical devices for monitoring diseases

    , Article Microchimica Acta ; Volume 189, Issue 7 , 2022 ; 00263672 (ISSN) Ebrahimi, G ; Samadi Pakchin, P ; Shamloo, A ; Mota, A ; de la Guardia, M ; Omidian, H ; Omidi, Y ; Sharif University of Technology
    Springer  2022
    The integration of microfluidics with electrochemical analysis has resulted in the development of single miniaturized detection systems, which allows the precise control of sample volume with multianalyte detection capability in a cost- and time-effective manner. Microfluidic electrochemical sensing devices (MESDs) can potentially serve as precise sensing and monitoring systems for the detection of molecular markers in various detrimental diseases. MESDs offer several advantages, including (i) automated sample preparation and detection, (ii) low sample and reagent requirement, (iii) detection of multianalyte in a single run, (iv) multiplex analysis in a single integrated device, and (v)... 

    Converting waste cooking oil into biodiesel using phosphomolybdic acid/clinoptilolite as an innovative green catalyst via electrolysis procedure; optimization by response surface methodology (RSM)

    , Article Fuel Processing Technology ; Volume 225 , 2022 ; 03783820 (ISSN) Helmi, M ; Tahvildari, K ; Hemmati, A ; Azar, P. A ; Safekordi, A ; Sharif University of Technology
    Elsevier B.V  2022
    The present study aims to convert waste cooking oil (WCO) into biodiesel via phosphomolybdic acid (H3PMo12O40, PMA) supported on Clinoptilolite as a novel green acid catalyst through an electrolysis procedure. The prepared catalysts were characterized by XRD, FTIR, FESEM, EDS, Elemental map, and TEM analyses. The effect of four independent variables on biodiesel yield including methanol to oil molar ratio (6:1–14:1), catalyst weight (2–5 wt%), time (3–5 h), and voltage (15–35 V) was optimized and evaluated by the response surface methodology (RSM) employing central composite design (CCD). The maximum value of biodiesel yield was 96% under the optimal conditions, including the methanol to oil... 

    Development of an Integrated Solar Energy System for a Typical Educational Building

    , M.Sc. Thesis Sharif University of Technology Motavaselian, Ali Mohammad (Author) ; Saboohi, Yadollah (Supervisor)
    In the present thesis, A Computer software has been developed to evaluate technical and economic aspects of photovoltaic systems, off-grid and on-grid configuration, in urban areas where the electricity grid is accessible. As a case study the building of Energy Engineering faculty with annual demand of electricity in lighting section equals to 80048 kWh was considered. Regarding incident radiation and PV system characteristics with the aid of utilizability concept, a technical evaluation has been performed then life-cycle saving index was considered as a criterion for choosing an optimum nominal size of the system. Results show that for current electricity tariff of educational buildings ... 

    A model-based approach for estimation of changes in lumbar segmental kinematics associated with alterations in trunk muscle forces

    , Article Journal of Biomechanics ; 2017 ; 00219290 (ISSN) Shojaei, I ; Arjmand, N ; Meakin, J. R ; Bazrgari, B ; Sharif University of Technology
    Elsevier Ltd  2017
    The kinematics information from imaging, if combined with optimization-based biomechanical models, may provide a unique platform for personalized assessment of trunk muscle forces (TMFs). Such a method, however, is feasible only if differences in lumbar spine kinematics due to differences in TMFs can be captured by the current imaging techniques. A finite element model of the spine within an optimization procedure was used to estimate segmental kinematics of lumbar spine associated with five different sets of TMFs. Each set of TMFs was associated with a hypothetical trunk neuromuscular strategy that optimized one aspect of lower back biomechanics. For each set of TMFs, the segmental... 

    A minimally invasive robotic surgery approach to perform totally endoscopic coronary artery bypass on beating hearts

    , Article Medical Hypotheses ; Volume 124 , 2019 , Pages 76-83 ; 03069877 (ISSN) Alamdar, A ; Hanife, S ; Farahmand, F ; Behzadipour, S ; Mirbagheri, A ; Sharif University of Technology
    Churchill Livingstone  2019
    The currently available robotic systems rely on rigid heart stabilizers to perform totally endoscopic coronary artery bypass (TECAB) surgery on beating hearts. Although such stabilizers facilitate the anastomosis procedure by immobilizing the heart and holding the surgery site steady, they can cause damage to the heart tissue and rupture of the capillary vessels, due to applying relatively large pressures on the epicardium. In this paper, we propose an advanced robotic approach to perform TECAB on a beating heart with minimal invasiveness. The idea comes from the fact that the main pulsations of the heart occur as excursions in normal direction, i.e., perpendicular to the heart surface. We... 

    Extraction of hydroxyapatite nanostructures from marine wastes for the fabrication of biopolymer-based porous scaffolds

    , Article Marine Drugs ; Volume 18, Issue 1 , 2020 Gheysari, H ; Mohandes, F ; Mazaheri, M ; Dolatyar, B ; Askari, M ; Simchi, A ; Sharif University of Technology
    MDPI AG  2020
    Three-dimensional porous nanocomposites consisting of gelatin-carboxymethylcellulose (CMC) cross-linked by carboxylic acids biopolymers and monophasic hydroxyapatite (HA) nanostructures were fabricated by lyophilization, for soft-bone-tissue engineering. The bioactive ceramic nanostructures were prepared by a novel wet-chemical and low-temperature procedure from marine wastes containing calcium carbonates. The effect of surface-active molecules, including sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB), on the morphology of HA nanostructures is shown. It is demonstrated that highly bioactive and monophasic HA nanorods with an aspect ratio > 10 can be synthesized in... 

    Design of a gain-scheduling anti-swing controller for tower cranes using fuzzy clustering techniques

    , Article CIMCA 2006: International Conference on Computational Intelligence for Modelling, Control and Automation, Jointly with IAWTIC 2006: International Conference on Intelligent Agents Web Technologies and International Commerce, Sydney, NSW, 28 November 2006 through 1 December 2006 ; 2006 ; 0769527310 (ISBN); 9780769527314 (ISBN) Sadati, N ; Hooshmand, A ; Sharif University of Technology
    IEEE Computer Society  2006
    The main objective of this paper is to design a fast,non-expensive and practical controller for towercranes. The controllers are designed to transfer theloads from point to point, as fast as possible, and at thesame time the load swing is kept small during thetransfer process. Moreover, variations of the systemparameters such as cable length are taken intoconsideration. It is shown how the state feedbackcontrollers along with the gain scheduling could beused for a time varying linear model with varyingparameters. For this reason, linear controllers aredesigned for a number of operating points, where theirparameters are interpolated for conditions in between.In this way, a globally nonlinear... 

    Nanotechnology-Abetted astaxanthin formulations in multimodel therapeutic and biomedical applications

    , Article Journal of Medicinal Chemistry ; Volume 65, Issue 1 , 2022 , Pages 2-36 ; 00222623 (ISSN) Jafari, Z ; Bigham, A ; Sadeghi, S ; Dehdashti, S. M ; Rabiee, N ; Abedivash, A ; Bagherzadeh, M ; Nasseri, B ; Karimi Maleh, H ; Sharifi, E ; Varma, R. S ; Makvandi, P ; Sharif University of Technology
    American Chemical Society  2022
    Astaxanthin (AXT) is one of the most important fat-soluble carotenoids that have abundant and diverse therapeutic applications namely in liver disease, cardiovascular disease, cancer treatment, protection of the nervous system, protection of the skin and eyes against UV radiation, and boosting the immune system. However, due to its intrinsic reactivity, it is chemically unstable, and therefore, the design and production processes for this compound need to be precisely formulated. Nanoencapsulation is widely applied to protect AXT against degradation during digestion and storage, thus improving its physicochemical properties and therapeutic effects. Nanocarriers are delivery systems with many... 

    A hybrid algorithm for prediction of varying heart rate motion in computer-assisted beating heart surgery

    , Article Journal of Medical Systems ; Volume 42, Issue 10 , 2018 ; 01485598 (ISSN) Mansouri, S ; Farahmand, F ; Vossoughi, G ; Alizadeh Ghavidel, A ; Sharif University of Technology
    Springer New York LLC  2018
    An essential requirement for performing robotic assisted surgery on a freely beating heart is a prediction algorithm which can estimate the future trajectory of the heart in the varying heart rate (HR) conditions of real surgery with a high accuracy. In this study, a hybrid amplitude modulation- (AM) and autoregressive- (AR) based algorithm was developed to enable estimating the global and local oscillations of the beating heart, raised from its major and minor physiological activities. The AM model was equipped with an estimator of the heartbeat frequency to compensate for the HR variations. The RMS of the prediction errors of the hybrid algorithm was in the range of 165–361 μm for the... 

    True damping and frequency prediction for aeroelastic systems: The PP method

    , Article Journal of Fluids and Structures ; Volume 25, Issue 7 , 2009 , Pages 1177-1188 ; 08899746 (ISSN) Haddadpour, H ; Firouz Abadi, R. D ; Sharif University of Technology
    This paper presents a numerical scheme for stability analysis of the aeroelastic systems in the Laplace domain. The proposed technique, which is called the PP method, is proposed for when the aerodynamic model is represented in the Laplace domain and includes complicated transcendental expressions in terms of the Laplace variable. This method utilizes a matrix iterative procedure to find the eigenvalues of the system and generalizes the other methods such as the P and PK methods for prediction of the flutter conditions. The major advantage of this technique over the other approximate methods is true prediction of subcritical damping and frequency values of the aeroelastic modes. To examine...