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Total 56 records

    Design of a 4 DOF laparoscopic surgery robot for manipulation of large organs

    , Article Studies in Health Technology and Informatics ; Volume 173 , 2012 , Pages 8-12 ; 09269630 (ISSN) ; 9781614990215 (ISBN) Alamdar, A ; Mirbagheri, A ; Farahmand, F ; Durali, M ; Sharif University of Technology
    2012
    Abstract
    In this paper, a 4-DOF robotic arm for tool handling in laparoscopic surgery is introduced. The robot provides sufficient force to handle endoscopic tools used for large organ manipulation and is capable of measuring the tool-tissue forces. The RCM constraint is achieved using a spherical mechanism and roll and insertion motions are provided using time pulley and spindle-drive, respectively. The forward and inverse kinematics of the robot was solved and the dimensions of its links were determined, using particle swarm optimization method, so that the maximum kinematic and dynamic performance could be achieved  

    Design and evaluation of vibratory shoe on balance control for elderly subjects: technical note

    , Article Disability and Rehabilitation: Assistive Technology ; Volume 13, Issue 2 , 2018 , Pages 173-177 ; 17483107 (ISSN) Aboutorabi, A ; Arazpour, M ; Farahmand, F ; Bahramizadeh, M ; Fadayevatan, R ; Abdollahi, E ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    Abstract
    Background and Aim: Aging often results in a decline in somatosensory function, and such changes are associated with diminished motor performance. Input noise can enhance sensory and motor function through a mechanism known as stochastic resonance (SR). This paper describes the development and testing of a new vibrating shoe to possibly assist the elderly patients in controlling their balance and decreasing their falling risks. Technique: The new vibrating shoe was evaluated to ascertain its ability to generate appropriate random and nonlinear vibrations. The vibratory shoe performance in two young subjects with decreased foot sensation and two elderly subjects in different static and... 

    Preparation, characterization, and applications of a novel solid-phase microextraction fiber by sol-gel technology on the surface of stainless steel wire for determination of poly cyclic aromatic hydrocarbons in aquatic environmental samples

    , Article Analytica Chimica Acta ; Vol. 813 , 2014 , pp. 48-55 ; ISSN: 00032670 Es-haghi, A ; Hosseininasab, V ; Bagheri, H ; Sharif University of Technology
    Abstract
    A novel solid-phase microextraction(SPME) fiber was prepared using sol-gel technology with ethoxylated nonylphenol as a fiber coating material. The fiber was employed to develop a headspace SPME-GC-MS method suitable for quantification of 13 polycyclic aromatic hydrocarbons (PAHs) in water samples. Surface characteristics of the fibers were inspected by energy dispersive X-ray (EDX) spectroscopy as well as by scanning electron microscopy (SEM). The SEM measurements showed the presence of highly porous nano-sized particles in the coating. Important parameters affecting the extraction efficiency such as extraction temperature and time, desorption conditions as well as ionic strength have been... 

    Modeling and velocity control of a-shape microrobot with adaptive neural network controller

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Vol. 4A, issue , 2014 Nojoumian, M. A ; Shirazi, M. J ; Vossoughi, G. R ; Salarieh, H ; Sharif University of Technology
    Abstract
    Design and control of micro robots have been one of the interesting fields in robotics in recent years. One class of these micro robots is the legged robots. Various designs of legged robots have been proposed in the literature. All designs rely on friction for locomotion. In this paper dynamic model of a planar two-legged micro robot is presented using Luger friction model, and an adaptive neural controller used to control the robot to improve robustness and velocity of the robot. As mentioned earlier, friction plays an important role in locomotion of the legged robots. However, especially in legged micro robots, it is difficult to model the frictional force correctly since environmental... 

    Modeling of a planar microrobot using lugre friction model

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 8, Issue PARTS A AND B , November , 2010 , Pages 633-639 ; 9780791844458 (ISBN) Khodabakhsh, M ; Vossoughi, G. R ; Kamali, A ; Sharif University of Technology
    2010
    Abstract
    Microrobots design and manufacturing has been one of interesting fields in robotics in recent years. Various legged designs have been proposed in the literature. All designs rely on friction for locomotion. In this paper the dynamic model of a planar two-legged microrobot is presented using LuGre friction model. LuGre friction model is more realistic model, reducing uncertainties of the microrobot dynamic model, providing a better prediction for both design and control applications. The proposed microrobot is driven by a piezoelectric actuator mounted between centers of two legs. One of important issues in modeling of microrobots is to determine the friction force between robot and... 

    Captopril: Reducing the pressure of bit flips on hot locations in non-volatile main memories

    , Article Proceedings of the 2016 Design, Automation and Test in Europe Conference and Exhibition, DATE 2016, 14 March 2016 through 18 March 2016 ; 2016 , Pages 1116-1119 ; 9783981537062 (ISBN) Jalili, M ; Sarbazi Azad, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    High static power consumption and insufficient scalability of the commonly used DRAM main memory technology appear to be tough challenges in upcoming years. Hence, adopting new technologies, i.e. non-volatile memories (NVMs), is a proper choice. NVMs tolerate a low number of write operations while having good scalability and low static power consumption. Due to the non-destructive nature of a read operation and the long latency of a write operation in NVMs, designers use read-before-write (RBW) mechanism to mask the unchanged bits during write operation in order to reduce bit flips. Based on this observation that some specific locations of blocks are responsible for the majority of bit... 

    Design and analysis of an original powered foot clearance creator mechanism for walking in patients with spinal cord injury

    , Article Disability and Rehabilitation: Assistive Technology ; Volume 14, Issue 4 , 2019 , Pages 333-337 ; 17483107 (ISSN) Maleki, M ; Badri, S ; Shayestehepour, H ; Arazpour, M ; Farahmand, F ; Mousavi, M. E ; Abdolahi, E ; Farkhondeh, H ; Head, J. S ; Golchin, N ; Mardani, M. A ; Sharif University of Technology
    Taylor and Francis Ltd  2019
    Abstract
    Background: The aim of this study was to assess the performance of an original powered foot clearance creator (PFCC) mechanism worn in conjunction with an isocentric reciprocal gait orthosis (IRGO) and evaluate its effect on trunk compensatory movements and spatiotemporal parameters in nine healthy subjects. Method: A PFCC motorized mechanism was designed that incorporated twin sole plates, the movements of which enabled increased toe to floor clearance during swing phase. A prototype was constructed in combination with an IRGO, and hence was re-named as an IRGO-PFCC orthosis. The effects of IRGO-PFCC usage on the spatiotemporal parameters and trunk compensatory movements during walking were... 

    An investigation into the energy transfer efficiency of a two-pigment photosynthetic system using a macroscopic quantum model

    , Article BioSystems ; Volume 197 , 2020 Ghasemi, F ; Shafiee, A ; Sharif University of Technology
    Elsevier Ireland Ltd  2020
    Abstract
    Despite several different measures of efficiency that are applicable to the photosynthetic systems, a precise degree of efficiency of these systems is not completely determined. Introducing an efficient model for the dynamics of light-harvesting complexes in biological environments is a major purpose in investigating such systems. Here, we investigate the effect of macroscopic quantum behavior of a system of two pigments on the transport phenomena in this system model which interacts with an oscillating environment. We use the second-order perturbation theory to calculate the time-dependent population of excitonic states of a two-dimensional Hamiltonian using a non-master equation approach.... 

    Comparison of strengths of five internal fixation methods used after bilateral sagittal split ramus osteotomy: An in vitro study

    , Article Dental Research Journal ; Volume 17, Issue 4 , 2020 , Pages 258-265 Sarkarat, F ; Ahmady, A ; Farahmand, F ; Fateh, A ; Kahali, R ; Nourani, A ; Rakhshan, V ; Sharif University of Technology
    Wolters Kluwer Medknow Publications  2020
    Abstract
    Results on the strength and displacement of internal fixation methods for bilateral sagittal split ramus osteotomy are controversial, and some designs have not been adequately studied. Therefore, this study was conducted to compare techniques using bicortical or monocortical screws. Materials and Methods: In this in vitro study, 35 sheep hemi-mandibles were randomly assigned to five groups of seven each: fixation using (1) a 13 × 2 screw, (2) two 13 × 2 screws (arranged vertically), (3) three 13 × 2 screws, (4) 1 plate with 4 holes and four monocortical screws, and (5) a Y-shaped plate and five monocortical screws. Specimens underwent vertical forces until failure. Breakage forces and... 

    Recent Progress of Triboelectric Nanogenerators for Biomedical Sensors: From Design to Application

    , Article Biosensors ; Volume 12, Issue 9 , 2022 ; 20796374 (ISSN) Rahimi Sardo, F ; Rayegani, A ; Matin Nazar, A ; Balaghiinaloo, M ; Saberian, M ; Mohsan, S. A. H ; Alsharif, M. H ; Cho, H. S ; Sharif University of Technology
    MDPI  2022
    Abstract
    Triboelectric nanogenerators (TENG) have gained prominence in recent years, and their structural design is crucial for improvement of energy harvesting performance and sensing. Wearable biosensors can receive information about human health without the need for external charging, with energy instead provided by collection and storage modules that can be integrated into the biosensors. However, the failure to design suitable components for sensing remains a significant challenge associated with biomedical sensors. Therefore, design of TENG structures based on the human body is a considerable challenge, as biomedical sensors, such as implantable and wearable self-powered sensors, have recently... 

    All-optical controlled switching in centrally coupled circular array of nonlinear optical fibers

    , Article Applied Optics ; Volume 52, Issue 25 , Sep , 2013 , Pages 6131-6137 ; 1559128X (ISSN) Tofighi, S ; Bahrampour, A. R ; Sharif University of Technology
    Optical Society of American (OSA)  2013
    Abstract
    We show that, in a nonlinear centrally coupled circular array of evanescently coupled fibers, the coupling dynamics of a weak signal beam can be efficiently influenced by a high-power control beam that induces nonlinear defects. When the intense control beam is launched into the central core and one core in the periphery, then localized solitons are formed and cause the fibers with induced defects (defected fibers) to decouple from the other array elements. In the presence of a high-intensity control beam, the propagation of weak signal is restricted to the defected optical fibers. The weak signal periodically couples between the induced defects. This oscillatory behavior depends on the sign... 

    Breakup of microdroplets in asymmetric T junctions

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 87, Issue 5 , 2013 ; 15393755 (ISSN) Samie, M ; Salari, A ; Shafii, M. B ; Sharif University of Technology
    2013
    Abstract
    Symmetric T junctions have been used widely in microfluidics to generate equal-sized microdroplets, which are applicable in drug delivery systems. A newly proposed method for generating unequal-sized microdroplets at a T junction is investigated theoretically and experimentally. Asymmetric T junctions with branches of identical lengths and different cross sections are utilized for this aim. An equation for the critical breakup of droplets at asymmetric T junctions and one for determining the breakup point of droplets are developed. A good agreement was observed between the theories (present and previous) and the experiments  

    Electromechanical resonator based on electrostatically actuated graphene-doped PVP nanofibers

    , Article Nanotechnology ; Volume 24, Issue 13 , 2013 ; 09574484 (ISSN) Fardindoost, S ; Mohammadi, S ; Zad, A. I ; Sarvari, R ; Shariat Panahi, S. P ; Jokar, E ; Sharif University of Technology
    2013
    Abstract
    In this paper we present experimental results describing electrical readout of the mechanical vibratory response of graphene-doped fibers by employing electrical actuation. For a fiber resonator with an approximate radius of 850 nm and length of 100 m, we observed a resonance frequency around 580 kHz with a quality factor (Q) of about 2511 in air at ambient conditions. Through the use of finite element simulations, we show that the reported frequency of resonance is relevant. We also show that the resonance frequency of the fiber resonators decreases as the bias potential is increased due to the electrostatic spring-softening effect  

    A triple-jaw actuated and sensorized instrument for grasping large organs during minimally invasive robotic surgery

    , Article International Journal of Medical Robotics and Computer Assisted Surgery ; Volume 9, Issue 1 , 2013 , Pages 83-93 ; 14785951 (ISSN) Mirbagheri, A ; Farahmand, F ; Sharif University of Technology
    2013
    Abstract
    Background: Secure grasping and effective manipulation of delicate large organs during robotic surgery operations needs especially designed instruments that can enclose a large amount of tissue and feed back the pinch forces. Methods: A large organ triple-jaw grasper was instrumented using practical force sensory and actuating systems. A force tracking scheme was proposed to facilitate auto-grasping of large organs during robotic teleoperation surgery. An on-site force commanding/reflecting mechanism was also implemented to use the device as an independent hand-held robotic instrument. The efficacy of the robotic grasper was examined in phantom tests. Results: The instrument grasped large... 

    Fully-Tunable microwave photonic filter with complex coefficients using tunable delay lines based on frequency-Time conversions

    , Article Optics Express ; Volume 20, Issue 20 , 2012 , Pages 22728-22734 ; 10944087 (ISSN) Mokhtari, A ; Preuler, S ; Jamshidi, K ; Akbari, M ; Schneider, T ; Sharif University of Technology
    Abstract
    A fully electrically tunable microwave photonic filter is realized by the implementation of delay lines based on frequency-Time conversion. The frequency response and free spectral range (FSR) of the filter can be engineered by a simple electrical tuning of the delay lines. The method has the capability of being integrated on a silicon photonic platform. In the experiment, a 2-Tap tunable microwave photonic filter with a 3-dB bandwidth of 2.55 GHz, a FSR of 4.016 GHz, a FSR maximum tuning range from -354 MHz to 354 MHz and a full FSR translation range is achieved  

    Influence of ridge filter material on the beam efficiency and secondary neutron production in a proton therapy system

    , Article Zeitschrift fur Medizinische Physik ; Volume 22, Issue 3 , September , 2012 , Pages 231-240 ; 09393889 (ISSN) Riazi, Z ; Afarideh, H ; Sadighi-Bonabi, R ; Sharif University of Technology
    Elsevier  2012
    Abstract
    In this work, the 3D proton dose profile is calculated in a homogenous water phantom using a Monte Carlo application developed with the Geant4 toolkit. The effect of the ridge filter material (for SOBP widths of 6, 9 and 12 cm) on the homogeneity of the dose distribution, secondary neutron production and beam efficiency are investigated in a single ring wobbling irradiation system. The energy spectrum of secondary neutrons per primary proton at various locations around the phantom surface is calculated. The simulation revealed that most of the produced neutrons are released at slight angles which enable them to reach the patient and consequently to be hazardous. Also, the homogeneity of the... 

    Trapezius muscle activity in using ordinary and ergonomically designed dentistry chairs

    , Article International Journal of Occupational and Environmental Medicine ; Volume 3, Issue 2 , Apr , 2012 , Pages 76-83 ; 20086520 (ISSN) Haddad, O ; Sanjari, M. A ; Amirfazli, A ; Narimani, R ; Parnianpour, M ; Sharif University of Technology
    Abstract
    Background: Most dentists complain of musculoskeletal disorders which can be caused by prolonged static posture lack of suitable rest and other physical and psychological problems. Objective: We evaluated a chair with a new ergonomic design which incorporated forward leaning chest and arm supports. Methods: The chair was evaluated in the laboratory during task simulation and EMG analysis on 12 students and subjectively assessed by 30 professional dentists using an 18-item questionnaire. EMG activity of right and left trapezius muscles for 12 male students with no musculoskeletal disorders was measured while simulating common tasks like working on the teeth of the lower jaw. Results:... 

    Diagnosing anterior cruciate ligament injuries using a knee arthrometer: Design, fabrication, and clinical evaluation

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 23, Issue 3 , April , 2011 , Pages 181-192 ; 10162372 (ISSN) Soudbakhsh, D ; Sahraei, E ; Shirin, M. B ; Farahmand, F ; Tahmasebi, M. N ; Parnianpour, M ; Sharif University of Technology
    2011
    Abstract
    Every year many people suffer from knee injuries. Previous studies on patients with knee injuries have shown that about 40% of knee injuries are Ligament injuries, and about 50% of the ligament injuries are the Anterior Cruciate Ligament (ACL) injuries. Along with other methods, knee arthrometers are widely used to diagnose ACL injuries. In the current research, a knee arthrometer was designed and developed to provide a reliable and repeatable measurement of knee laxity under anteriorposterior applied loads. Testretest configurations to examine repeatability of the device resulted in less than 1.5-mm difference for more than 97% of tests under applied loads of up to 90 N. These tests... 

    MVC app: A smartphone application for performing chemometric methods

    , Article Chemometrics and Intelligent Laboratory Systems ; Volume 147 , October , 2015 , Pages 105-110 ; 01697439 (ISSN) Parastar, H ; Shaye, H ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In this work, a novel smartphone application entitled ". MVC app" is developed to perform different multivariate calibration methods. This app is designed for chemists who are not expert in programming or in advanced statistics. The developed application can use any Android-powered device as an environment for running. It is an easy to use app which can simply install in your smartphone and play. Different multivariate calibration methods, such as multiple linear regression (MLR), principal component regression (PCR) and partial least squares (PLS) are included in this app. As an instance, for performing PLS modeling, first calibration and validation data sets are imported (via USB or... 

    Characteristic ratio assignment in fractional order systems

    , Article ISA Transactions ; Volume 49, Issue 4 , October , 2010 , Pages 470-478 ; 00190578 (ISSN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    2010
    Abstract
    In this paper the characteristic ratios and generalized time constant are defined for all-pole commensurate fractional order systems. The sufficient condition for stability of these systems in terms of their characteristic ratios is obtained. Also an analytical approach for characteristic ratio assignment (CRA) to have a non-overshooting fast closed loop step response is introduced. The proposed CRA method is then employed to design a fractional order controller. Computer simulation results are presented to illustrate the performance of the CRA based designed fractional order controllers