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    Fabrication of 3D Graphene/Gold Porous Electrode for Biosensing Applications

    , M.Sc. Thesis Sharif University of Technology Rahmati, Reza (Author) ; Simchi, AbdolReza (Supervisor) ; Tamjid Shabestari, Elnaz (Supervisor)
    Abstract
    Today, the use of carbon nanostructures hybridized with noble metals has attracted considerable attention for the fabrication of bio-electrochemical sensors. Since the specific surface area has an immense effect on the sensing response, three-dimensional structures of graphene have a great capability to utilize in these sensors. In this research, three-dimensional graphene was provided on the porous nickel foam by chemical vapor deposition technique. By evaluation of raman spectroscopy, the time period of 20 minutes for solving of the carbon atoms into the nickel foam was selected as the main parameter of optimized conditions for the synthesis of graphene. Afterward, production of few-layer... 

    Bio-inspired nanostructured sensor for the detection of ultralow concentrations of explosives [electronic resource]

    , Article Journal of Angewandte Chemie International Edition ; 29 May 2012, Volume 51, Issue 22, P.5334-5338 Dourandish, M. (Mahdi) ; Simchi, A. (Abdolreza) ; Tamjid Shabestary, Elnaz ; Hartwig, Thomas ; Sharif University of Technology
    Abstract
    TNT: Silicon microcantilevers modified with a three-dimensional layer of vertical titanium dioxide nanotubes can be used in micromechanical sensors with optical signal detection to detect low levels of explosives such as 2,4,6-trinitrotoluene (TNT) in the gas phase, even in the presence of other volatile impurities such as n-heptane and ethanol  

    Surface Modification of Bacterial Cellulose-Reinforced Keratin Nanofibers using Pluronic/Gum Tragacanth Hydrogel Nanoparticles Produced by Concurrent gel Electrospray/Polymer Electrospinning Method

    , M.Sc. Thesis Sharif University of Technology Azarniya, Amir (Author) ; Simchi, Abdolreza (Supervisor) ; Tamjid, Elnaz (Supervisor)
    Abstract
    In this work, wool keratin/polyethylene oxide (PEO) nanofibrous scaffolds were fabricated by electrospinning method. Bacterial cellulose nanofibrils (BCNFs) were embedded in the electrospun keratin/PEO nanofibers. Incorporation of BCNFs into the nanofibers enhances their hydrophilicity, mechanical properties and cell viability, adhesion and proliferation. Water contact angle of the nanofibers decreased from 126˚ to 83˚by addition of 1 wt % BCNFs. A thermogelling hydrogel based on carboxylated pluronic (Pl-COOH) and gum tragacanth (GT) was fabricated and polymer conjugation was confirmed by FTIR and H-NMR spectroscopy. Morphological and viscoelastic properties of GT-grafted Pl-COOH hydrogels... 

    Generation and Optimization of High-order Harmonics in the Interaction of Laser with N2O Molecule

    , M.Sc. Thesis Sharif University of Technology Monfared, Mohammad (Author) ; Sadighi-Bonabi, Rasoul (Supervisor) ; Irani, Elnaz (Co-Supervisor)
    Abstract
    The X-ray attosecond pulses have many useful applications for studying atomic and sub-atomic scales phenomena in attosecond scale duration. Generation and optimization of high-order harmonics is an efficient way to produce such attosecond pulses which are studied in this thesis. There are several limitations in the attosecond pulse generation such as low efficiency of high-order harmonics, long duration of output pulses and the impossibility of producing an attosecond pulse with any desired wavelength in the x-ray region. Therefore, more investigations into high harmonic generation and fully control and optimization of this process is significant. In this thesis, high harmonic generation... 

    Sensitive Detection and Quantification of Nitrite Ions by Metal-organic Frameworks/Gold Nanocomposites

    , M.Sc. Thesis Sharif University of Technology Mahdavi, Hossein (Author) ; Simchi, Abdoolreza (Supervisor) ; Tamjid Shabestari, Elnaz (Supervisor)
    Abstract
    Nitrite (〖NO〗_2^-) anions are ubiquitous within the physiological, industrial, environmental, and food industries. The potential toxicity risk of these inorganic compounds has well been recognized; thus, the precise detection of these ions by developing reliable and high-throughput analytical methods is crucial for health and environment security. In this study, we present a reagentless electrochemical biosensor using cobalt-based metal-organic frameworks (ZIF-67) and gold nanoparticles (Au NPs) for determination of nitrite ions. The developed biosensor provides the advantages of MOF properties including high surface area, hierarchical porosity, and tunable functionalities along with high... 

    A Deep Learning Approach to Classify Motor Imagery Based on The Combination of Discrete Wavelet Transform and Convolutional Neural Network for Brain Computer Interface System

    , M.Sc. Thesis Sharif University of Technology Elnaz Azizi (Author) ; Selk Ghafari, Ali (Supervisor) ; Zabihollah, Abolghssem (Supervisor)
    Abstract
    A Brain-Computer Interface (BCI) is a communication system that does not need any peripheral muscular activity. The huge goal of BCI is to translate brain activity into a command for a computer. One of the most important topics in the brain-computer interface is motor imagery (MI), which shows the reconstruction of subjects. The electrical activities of the brain are measured as electroencephalogram (EEG). EEG signals behave as low to noise ratio also show the dynamic behaviors.In the present work, a novel approach has been employed which is based on feature extraction with discretion wavelet transform (DWT), support vector machine (SVM), Artificial Neural Network (ANN) and Convolutional... 

    Tissue growth into three‐dimensional composite scaffolds with controlled micro‐features and nanotopographical surfaces [electronic resource]

    , Article Journal of Biomedical Materials Research Part A ; October 2013, Vol. 101, Issue 10, Pages 2796-2807 Tamjid, E. (Elnaz) ; Simchi, A. (Abdolreza) ; Dunlop, John W. C ; Fratzl, Peter ; Bagheri, R ; Vossoughi, M ; Sharif University of Technology
    Abstract
    Controlling topographic features at all length scales is of great importance for the interaction of cells with tissue regenerative materials. We utilized an indirect three-dimensional printing method to fabricate polymeric scaffolds with pre-defined and controlled external and internal architecture that had an interconnected structure with macro- (400-500 μm) and micro- (∼25 μm) porosity. Polycaprolactone (PCL) was used as model system to study the kinetics of tissue growth within porous scaffolds. The surface of the scaffolds was decorated with TiO2 and bioactive glass (BG) nanoparticles to the better match to nanoarchitecture of extracellular matrix (ECM). Micrometric BG particles were... 

    Kinetic Euclidean minimum spanning tree in the plane

    , Article Journal of Discrete Algorithms ; Volume 16 , October , 2012 , Pages 2-11 ; 15708667 (ISSN) Rahmati, Z ; Zarei, A ; Sharif University of Technology
    Elsevier  2012
    Abstract
    This paper presents a kinetic data structure (KDS) for maintenance of the Euclidean minimum spanning tree (EMST) on a set of moving points in 2-dimensional space. For a set of n points moving in the plane we build a KDS of size O(n) in O(nlogn) preprocessing time by which the EMST is maintained efficiently during the motion. This is done by applying the required changes to the combinatorial structure of the EMST which is changed in discrete timestamps. We assume that the motion of the points, i.e. x and y coordinates of the points, are defined by algebraic functions of constant maximum degree. In terms of the KDS performance parameters, our KDS is responsive, local, and compact. The... 

    Kinetic Euclidean minimum spanning tree in the plane

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 7056 LNCS , 2011 , Pages 261-274 ; 03029743 (ISSN) ; 9783642250101 (ISBN) Rahmati, Z ; Zarei, A ; Sharif University of Technololgy
    2011
    Abstract
    This paper presents the first kinetic data structure (KDS) for maintenance of the Euclidean minimum spanning tree (EMST) on a set of n moving points in 2-dimensional space. We build a KDS of size O(n) in O(nlogn) preprocessing time by which their EMST is maintained efficiently during the motion. In terms of the KDS performance parameters, our KDS is responsive, local, and compact  

    Combinatorial changes of euclidean minimum spanning tree of moving points in the plane

    , Article Proceedings of the 22nd Annual Canadian Conference on Computational Geometry, CCCG 2010, 9 August 2010 through 11 August 2010, Winnipeg, MB ; 2010 , Pages 43-45 Rahmati, Z ; Zarei, A ; Sharif University of Technology
    2010
    Abstract
    In this paper, we enumerate the number of combinatorial changes of the the Euclidean minimum spanning tree (EMST) of a set of n moving points in 2- dimensional space. We assume that the motion of the points in the plane, is defined by algebraic functions of maximum degree s of time. We prove an upper bound of O(n3β2s(n2)) for the number of the combinatorial changes of the EMST, where βs(n)= λs(n)/n and λs(n) is the maximum length of Davenport-Schinzel sequences of order s on n symbols which is nearly linear in n. This result is an O(n) improvement over the previously trivial bound of O(n4)  

    Analysis and design of a cable-driven mechanism for a spherical surgery robot

    , Article 2015 22nd Iranian Conference on Biomedical Engineering, ICBME 2015, 25 November 2015 through 28 November 2015 ; 2015 , Pages 221-226 ; 9781467393515 (ISBN) Rahmati, Z ; Behzadipour, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    This paper presents design and analysis of a cabledriven mechanism for a spherical laparoscopy surgical robot manufactured at the Research Center for Science and Technology in Medicine. The design is featured by two types of 'idler pulleys', which allow change of cables' plane of motion in spherical workspace. This robot suffers from back-lash and high friction due to the usage of motor and gear-box in each joint. In order to find a precise and optimal design, the paper studies various designs of cable robots, considering pulleys and cable arrangements, as well as pre-tensioning methods. Final scheme introduces two series of pulleys for each DOF, which transmits power from motors located on... 

    Control tuning of a اeart motion tracking system in off-pump heart surgery

    , Article 5th RSI International Conference on Robotics and Mechatronics, IcRoM 2017, 25 October 2017 through 27 October 2017 ; 2018 , Pages 445-450 ; 9781538657034 (ISBN) Rahmati, Z ; Behzadipour, S ; Sharif University of Technology
    2018
    Abstract
    Design, implementation and experimental evaluation of a classic PID, and a modern Generalized Predictive Control (GPC) for an off-pump heart tracking system were carried out. Following the design and simulation analysis of the controllers, experimental evaluation was conducted on the slave robot of SINA tele-operational surgical system. Results revealed that considering the volatile high-frequency/speed pattern of heart motion, the agility of the controlled system is the most influential factor on its performance. With this in mind, unlike the Ziegler-Nichols-based tuned PID with emphasis on steady-state condition, the PID control with more transient behavior showed a superior performance.... 

    Control tuning of a اeart motion tracking system in off-pump heart surgery

    , Article 5th RSI International Conference on Robotics and Mechatronics, IcRoM 2017, 25 October 2017 through 27 October 2017 ; 2018 , Pages 445-450 ; 9781538657034 (ISBN) Rahmati, Z ; Behzadipour, S ; Sharif University of Technology
    Elsevier  2018
    Abstract
    Design, implementation and experimental evaluation of a classic PID, and a modern Generalized Predictive Control (GPC) for an off-pump heart tracking system were carried out. Following the design and simulation analysis of the controllers, experimental evaluation was conducted on the slave robot of SINA tele-operational surgical system. Results revealed that considering the volatile high-frequency/speed pattern of heart motion, the agility of the controlled system is the most influential factor on its performance. With this in mind, unlike the Ziegler-Nichols-based tuned PID with emphasis on steady-state condition, the PID control with more transient behavior showed a superior performance.... 

    Evaluation of geopolymer concrete at high temperatures: An experimental study using machine learning

    , Article Journal of Cleaner Production ; Volume 372 , 2022 ; 09596526 (ISSN) Rahmati, M ; Toufigh, V ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Studying the mechanical performance of concrete after being exposed to high temperatures is an important step in the damage assessment of buildings and fire safety applications. However, predicting the compressive strength of GPC accurately after exposure to high temperatures is a challenging task. In this paper, artificial neural network (ANN) and support vector regression (SVR) models were developed to predict the compressive strength of geopolymer concrete (GPC) at high temperatures ranging from 100 °C to 1000 °C. A series of experiments consisting of different mix designs were conducted at elevated temperatures to prepare a dataset. Besides experiments' results, the data of previously... 

    Escort patterns in dual-worker households with students

    , Article Journal of Soft Computing in Civil Engineering ; Volume 5, Issue 1 , 2021 , Pages 62-79 ; 25882872 (ISSN) Rahmati, Y ; Samimi, A ; Sharif University of Technology
    Pouyan Press  2021
    Abstract
    Individuals have been regarded as independent decision makers in majority of transportation analysis. However, agents’ behaviors are usually affected by the interactions among the members in a group; and therefore, individual decision-making paradigms may result in unrealistic outcomes and erroneous interpretations of the results. In light of this, the present study develops discrete choice models in individual and group levels and compares their prediction power in predicting the choice of escort pattern in dual-worker households with at least one under-18-year-old student. The main purpose is to reveal the efficiency of each approach in analyzing parent-child joint activities and highlight... 

    Investigating Geometric Proximity Problems on Moving Points

    , M.Sc. Thesis Sharif University of Technology Rahmati, Zahed (Author) ; Zarei, Alireza (Supervisor)
    Abstract
    An interesting theoretical and practical set of problems in computer science is concerned with the study of spatial relations among objects in a geometric space. Examples of such problems for a set of points P are finding the closest pair of the points P, partitioning space into regions such that all points of a region have minimum distance to the same point in P, and computing the Euclidean minimum spanning tree on P. Moreover, we need mechanisms to efficiently update these properties when the points P are allowed to move or may be inserted or deleted. This is to avoid re-computation of these properties from scratch. Here, we consider the Euclidean minimum spanning tree (EMST) of a set of... 

    Escort patterns in Dual-worker households with Students: A Comparison between Individual and Group Decision Making Mechanism

    , M.Sc. Thesis Sharif University of Technology Rahmati, Yalda (Author) ; Samimi, Amir (Supervisor)
    Abstract
    Individuals have been regarded as independent decision makers in the majority of transportation analysis. However, individual behaviors are usually affected by the interactions between the members in group decisions; and consequently, individual decision making paradigm could result in less-accurate predictions. Besides, as the data used for travel demand modeling typically comes from household level surveys, the idea of random sampling holds at household level and not the individual; and therefore, individual information would not be consistent with the theory of the discrete choice models when the household is the actual sampling unit. The present paper aims at modeling the way that... 

    Control of Two Degree of Freedom Underactuated Systems

    , M.Sc. Thesis Sharif University of Technology Rahmati, Rahman (Author) ; Namvar, Mehrzad (Supervisor)
    Abstract
    In robotic, Underactuated systems are interesting subject to study. Underactuated system, is a system that have fewer actuator than degrees of freedom. Underactuated systems are composed of active and passive joints. passive joints are existed, in order to decrease the weight, cost, and energy consumption. Usually, control of these systems are difficult. Underactuated systems have acceleration constraint. This property make the control method have fundamental constraint. So that controller dynamic could not be a smooth function of states of system. So most of standard method in control, such as feedback linearization, are not applicable. Local linearizing methods, because of... 

    Damage Detection and Health Monitoring of Geopolymer Concrete Using Ultrasound Waves and Machine Learning

    , M.Sc. Thesis Sharif University of Technology Rahmati, Mohammad (Author) ; Toufigh, Vahab (Supervisor)
    Abstract
    The behavior of construction materials at high temperatures has been an important aspect of researches in recent years. The first part of the current research aims to non-destructively monitor the formation and growth of damage at geopolymer concrete (GPC) after being exposed to high temperatures using linear and nonlinear ultrasonic techniques. Ultrasonic waveform and pulse velocity (UPV) tests were conducted on the specimens before and after exposure to the temperatures. Nonlinear wave signals were processed in phase-space domain for qualitative health monitoring of GPC. Furthermore, feature extraction was applied to phase-plane attractors using fractal dimension for quantitative... 

    A Novel Resource Allocation Algorithm in Edge Computing with Deep Reinforcement Learning

    , M.Sc. Thesis Sharif University of Technology Rahmati, Iman (Author) ; Movaghar, Ali (Supervisor)
    Abstract
    With the explosion of mobile smart devices, many computation intensive applications have emerged, such as interactive gaming and augmented reality. Mobile edge computing (EC) is put forward, as an extension of cloud computing, to meet the low-latency require- ments of the applications. In mobile edge computing systems, an edge node may have a high load when a large number of mobile devices offload their tasks to it. those offloaded tasks may experience large processing delay or even be dropped when their deadlines expire. Due to the uncertain load dynamics at the edge nodes, it is challenging for each device to determine its offloading decision (i.e., whether to offload or not, and which...