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    , M.Sc. Thesis Sharif University of Technology Ghods, Masoud (Author) ; Bozorgmehri, Ramin (Supervisor)
    Abstract
    Application of the advanced control techniques and information technology in the biomedical engineering have been the focal point of the research communities in biomedical engineering due to the rapid growth of the nonlinear control theories along with the computer hardware. In this work the application of differential geometry and globally linearizing control has been applied to efficiently control the first phase of HIV disease based on the HIV infection model proposed in the literature. All the efforts have been in the way to obtain a suitable scenario of drug administration to suppress and control the infection. In the proposed scenario, drug administration is time dependant and... 

    Contract Modifications for Controlling Unnecessary Work Scope Changes in Public Construction Projects in Iran

    , M.Sc. Thesis Sharif University of Technology Ghods, Peyman (Author) ; Eslami, Hossein (Supervisor)
    Abstract
    Variation in value and initial cost of construction contracts in many cases lead to considerably increasing the finalized price. These increases are sometimes so big enough that the 25 percent of limitation which could be added to contracts couldn't make them to be finalized and exploitable, so the necessity of a new contract sometimes up to 100 percent or even up to 200 percent of initial cost for completing the same project is inevitable. Although in some specific and rare cases we couldn't avoidance from these changes, but observing the growth of these changes in public construction projects of Iran increase the requirement of special attention in order to find the main causes, prevention... 

    Plasmonic enhancement of photocurrent generation in two-dimensional heterostructure of WSe2/MoS2

    , Article Nanotechnology ; Volume 32, Issue 32 , 2021 ; 09574484 (ISSN) Ghods, S ; Esfandiar, A ; Sharif University of Technology
    IOP Publishing Ltd  2021
    Abstract
    Enhancing the photoresponse of single-layered semiconductor materials is a challenge for high-performance photodetectors due to atomically thickness and limited quantum efficiency of these devices. Band engineering in heterostructure of transition metal chalcogenides (TMDs) can sort out part of this challenge. Here, we address this issue by utilizing the plasmonics phenomenon to enrich the optoelectronics property of the WSe2/MoS2 heterojunction and further enhancement of photoresponse. The introduced approach presents a contamination-free, tunable and efficient way to improve light interactions with heterojunction devices. The results showed a 3600-fold enhancement in photoresponsivity and... 

    Addressing the epistemic uncertainty in seismic hazard analysis as a basis for seismic design by emphasizing the knowledge aspects and utilizing imprecise probabilities

    , Article Bulletin of Earthquake Engineering ; 2021 ; 1570761X (ISSN) Ghods, B ; Rahimzadeh Rofooei, F ; Sharif University of Technology
    Springer Science and Business Media B.V  2021
    Abstract
    Epistemic uncertainty in seismic hazard analysis is traditionally addressed by utilizing a logic-tree structure with subjective probabilities for branches. However, many studies have argued that probability is not a suitable choice for addressing epistemic uncertainties; in particular in addressing the background knowledge supporting the probabilities. In this regard, the application of imprecise probability (IP) is investigated. It is discussed that IP could provide a flexible tool for a more objective presentation of experts' knowledge. Moreover, the importance of addressing the strength of knowledge and surprises relative to knowledge in seismic hazard analysis along with methods to do... 

    Application of mean-covariance regression methods for estimation of edp|im distributions for small record sets

    , Article Journal of Earthquake Engineering ; 2021 ; 13632469 (ISSN) Ghods, B ; Rahimzadeh Rofooei, F ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    Abstract
    The performance of several regression methods is investigated to estimate the distribution of engineering demand parameters conditioned on intensity measures (EDP|IM) for small record sets. In particular, the performance of the multivariate ordinary least squares (OLS), a simultaneous mean-variance regression (MVR) done by a penalized weighted least-square loss function, and a mean-covariance/variance regression based on expectation maximization method (EM) are assessed. The efficiency of the introduced methods is compared with FEMA-P58 methodology. Performance assessment of EM and MVR methods shows that the overall increase in efficiency is about 25–45% for maximum inter-story drift ratios,... 

    Application of mean-covariance regression methods for estimation of edp|im distributions for small record sets

    , Article Journal of Earthquake Engineering ; Volume 26, Issue 14 , 2022 , Pages 7276-7296 ; 13632469 (ISSN) Ghods, B ; Rofooei, F. R ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    The performance of several regression methods is investigated to estimate the distribution of engineering demand parameters conditioned on intensity measures (EDP|IM) for small record sets. In particular, the performance of the multivariate ordinary least squares (OLS), a simultaneous mean-variance regression (MVR) done by a penalized weighted least-square loss function, and a mean-covariance/variance regression based on expectation maximization method (EM) are assessed. The efficiency of the introduced methods is compared with FEMA-P58 methodology. Performance assessment of EM and MVR methods shows that the overall increase in efficiency is about 25–45% for maximum inter-story drift ratios,... 

    Addressing the epistemic uncertainty in seismic hazard analysis as a basis for seismic design by emphasizing the knowledge aspects and utilizing imprecise probabilities

    , Article Bulletin of Earthquake Engineering ; Volume 20, Issue 2 , 2022 , Pages 741-764 ; 1570761X (ISSN) Ghods, B ; Rofooei, F. R ; Sharif University of Technology
    Springer Science and Business Media B.V  2022
    Abstract
    Epistemic uncertainty in seismic hazard analysis is traditionally addressed by utilizing a logic-tree structure with subjective probabilities for branches. However, many studies have argued that probability is not a suitable choice for addressing epistemic uncertainties; in particular in addressing the background knowledge supporting the probabilities. In this regard, the application of imprecise probability (IP) is investigated. It is discussed that IP could provide a flexible tool for a more objective presentation of experts' knowledge. Moreover, the importance of addressing the strength of knowledge and surprises relative to knowledge in seismic hazard analysis along with methods to do... 

    Performance Evaluation of Piezoelectric Based Control System to Mitigate the Vibration of Bridges Caused by Traffic Loads and Seismic Excitation

    , M.Sc. Thesis Sharif University of Technology Ghods, Babak (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    Abstract
    A large number of bridges in Iran are deteriorating under long and heavy traffic loadings, while getting closer to the end of their design life time. Therefore, many of them have been exhibiting various problems such as excessive vibration or large deflection under the normal service loadings. So, mitigating traffic-induced bridge vibration and damages is necessary to extend their efficient period of serviceability. On the other hand, application of active and passive control devices in structural retrofitting have absorbed the attention of many engineers and researchers. In this work, the performance of an active control system made of piezoelectric actuators is investigated in reducing the... 

    Risk-Based Seismic Design of Buildings in the Context of Cities,with Rigorous Uncertainty Modeling, and Proposing Efficient Computational Methods

    , Ph.D. Dissertation Sharif University of Technology Ghods, Babak (Author) ; Rahimzadeh Rofooei, Fayaz (Supervisor)
    Abstract
    The main goal of the current building design codes is to protect life safety, and generally, they do not directly address other societal, economic, etc., concerns regarding earthquakes. However, recent earthquakes around the world have shown that the effects of earthquakes' damages and losses can go beyond life-safety concerns. This observation has led many renowned scholars, organizations, and agencies to state the need to change the current design codes. In this regard, this thesis investigates the basis of setting the seismic design requirements and suggests a method in this respect. The study consists of two main parts. Part I (theory and design methodology) discusses some theoretical... 

    Introducing a Simulation-Based Model to Improve the Design and Layout of Workstations Inside Airport Terminals in Iran

    , M.Sc. Thesis Sharif University of Technology Amini Esfidvajani, Amin Mohammad (Author) ; Alvanchi, Amin (Supervisor)
    Abstract
    The airport terminal is difficult to plan and design due to the different components and the intricate complexity of its parts. At the airport terminal, we face a queue system which simulation is always a good way to analyze. In addition, computer simulation using modern softwares with the capability to model different types of systems, including the airport terminal, while being less realistic than analytical models, is less costly than operational Exercise.In this study, a supportive approach for better and specific management of Iranian airport terminal buildings with discrete-event simulation is proposed, considering the need for managing the airport terminals building in the country and... 

    A Multi-channel Scheme for Fast Data Collection in Wireless Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Ghods, Fatemeh (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor)
    Abstract
    With the development of technology and growing interest in using high performance and low price products, Wireless Sensor Networks (WSNs) are being dramatically deployed as an emerging technology. The main concern in WSNs is energy consumption that has an effect on sensor’s life time. In order to minimize the energy consumption, Data aggregation, which obtains aggregated values from WSNs, is an important functionality but yet time consuming. On the other hands, Emerging applications of Wireless Sensor Networks (WSNs) such as real-time detection of events need high-rate data collection, which is now an important challenge in WSNs. Multi-channel communication is one of the efficient methods to... 

    Design improvement of a small, outer rotor, permanent magnet vernier generator for supplying traffic enforcement camera

    , Article IEEE Transactions on Energy Conversion ; Volume 33, Issue 3 , 2018 , Pages 1213-1221 ; 08858969 (ISSN) Ghods, M ; Nasiri Gheidari, Z ; Tootoonchian, F ; Oraee, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Road speed cameras are usually used in photovoltaic power plants, especially in the areas with limited or no access to grid power. However, there are many areas in Iran where wind power is more accessible than solar energy. So, in this study, a small permanent magnet vernier generator is designed to meet power concussion requirements of traffic enforcement camera. The designed generator is optimized to achieve lower harmonic content of no-load induced voltage and lower cogging torque. In this regard, the effect of geometrical dimensions and the configuration of permanent magnets are investigated using three-dimensional time stepping finite element method. Both no-load and full-load... 

    Enhanced photoresponse and wavelength selectivity by silar-coated quantum dots on two-dimensional WSe2Crystals

    , Article ACS Omega ; Volume 7, Issue 2 , 2022 , Pages 2091-2098 ; 24701343 (ISSN) Ghods, S ; Esfandiar, A ; Iraji Zad, A ; Vardast, S ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    High-performance photodetectors play crucial roles as an essential tool in many fields of science and technology, such as photonics, imaging, spectroscopy, and data communications. Demands for desired efficiency and low-cost new photodetectors through facile manufacturing methods have become a long-standing challenge. We used a simple successive ionic layer adsorption and reaction (SILAR) method to synthesize CdS, CdSe, and PbS nanoparticles directly grown on WSe2 crystalline flakes. In addition to the excellent wavelength selectivity for (30 nm) CdS, (30 nm) CdSe, and (6 nm) PbS/WSe2 heterostructures, the hybrid devices presented an efficient photodetector with a photoresponsivity of 48.72... 

    , M.Sc. Thesis Sharif University of Technology (Author) ; Alvanchi, Amin (Supervisor)
    Abstract
    Limited water resources in Iran have made dams an important part of the country’s infrastructure. As a result of the large number of in-progress and expected dam projects in the country, consideration of sustainability factors during planning, construction and operation phases of dam projects can create significant economical, social and environmental impacts in the long term. To come up with an inclusive sustainable development, new sustainability assessment approaches seek for sustainable development at the entire project’s life-cycle; they are looking for sustainable development at all design, construction, operation, maintenance and even demolition phases. In this research we have... 

    MC-MLAS: Multi-channel Minimum Latency Aggregation Scheduling in Wireless Sensor Networks

    , Article Computer Networks ; Volume 57, Issue 18 , December , 2013 , Pages 3812-3825 ; 13891286 (ISSN) Ghods, F ; Yousefi, H ; Afshin Hemmatyar, A. M ; Movaghar, A ; Sharif University of Technology
    2013
    Abstract
    Data aggregation is a key, yet time-consuming functionality in wireless sensor networks (WSNs). Multi-channel design is a promising technique to alleviate interference as a primary reason for long latency of TDMA aggregation scheduling. Indeed, it provides more potential of parallel transmissions over different frequency channels, thus minimizing time latency. In this paper, we focus on designing a multi-channel minimum latency aggregation scheduling protocol, named MC-MLAS, using a new joint approach for tree construction, channel assignment, and transmission scheduling. To our best knowledge, this is the first work in the literature which combines orthogonal channels and partially... 

    Performance Analysis, Optimization and Prototyping of Doubly Salient PM Vernier Generators

    , M.Sc. Thesis Sharif University of Technology Ghods, Mehrage (Author) ; Oraee, Hashem (Supervisor) ; Nasiri-Gheidari, Zahra (Supervisor)
    Abstract
    In this thesis, no-load and full-load performance of Permanent Magnet Vernier Generators (PMVGs) is investigated in fully-aligned condition and under different types of mechanical faults. The studied mechanical faults are Static Eccentricity (SE), Dynamic Eccentricity (DE), Inclined Rotor (IR), and Run-out (RO). Furthermore, an analytical model is also developed to calculate the permeance of the air-gap and the induced voltages in the health machine and under studied mechanical faults. Then, 2-D and 3-D non-linear, time stepping finite element method is utilized for performance evaluation of the generator in no-load and full-load (with resistive, inductive and capacitive loads). In continue,... 

    Nonlinear behavior of connections in RCS frames with bracing and steel plate shear wall

    , Article Steel and Composite Structures ; Volume 22, Issue 4 , 2016 , Pages 915-935 ; 12299367 (ISSN) Ghods, S ; Kheyroddin, A ; Nazeryan, M ; Mirtaheri, S. M ; Gholhaki, M ; Sharif University of Technology
    Techno Press  2016
    Abstract
    Steel systems composed of Reinforced Concrete column to Steel beam connection (RCS) have been raised as a structural system in the past few years. The optimized combination of steel-concrete structural elements has the advantages of both systems. Through beam and through column connections are two main categories in RCS systems. This study includes finite-element analyses of mentioned connection to investigate the seismic performance of RCS connections. The finite element model using ABAQUS software has been verified with experimental results of a through beam type connection tested in Taiwan in 2005. According to verified finite element model a parametric study has been carried out on five... 

    Enhanced Broadband Photoresponsivity of the CZTS/WSe2Heterojunction by Gate Voltage

    , Article ACS Applied Electronic Materials ; Volume 4, Issue 12 , 2022 , Pages 6189-6203 ; 26376113 (ISSN) Ghods, S ; Vardast, S ; Esfandiar, A ; Iraji Zad, A ; Heidariramsheh, M ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    High-performance photodetectors play critical roles in numerous photon-based applications in imaging, communication, and energy harvesting. Nowadays, heterostructures have received significant attention to extend the performance of photodetectors, with exceptionally high optical absorption and a wide absorption range. However, the enhancement factors, exact mechanism, and facile fabrication procedures are long-standing problems. Here, a heterojunction of a two-dimensional chemical vapor deposition-grown monolayer of WSe2with a Cu2ZnSnS4(CZTS) film is introduced. The CZTS film as an abundant material was synthesized in the form of nanoparticles, and it showed a great effect on the enhancement... 

    Evaluating the Effects of Aftershocks on Increasing the Structural Damages in Special Steel Moment Frame Building

    , M.Sc. Thesis Sharif University of Technology Hajili, Ronak (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor) ; Ghods, Babak (Co-Supervisor)
    Abstract
    The purpose of this study is to investigate the effect of consecutive earthquakes by considering different levels of structural damage intensity index. The cumulative damage of structures caused by the sequence of main earthquake and aftershock is a combination of the initial damage caused by the main earthquake and the increased damage caused by the aftershock. The evaluation process of the main earthquake and aftershock is divided into two parts: evaluation of the fragility of the main earthquake and evaluation of the fragility due to the aftershock. This investigation was carried out using a 4-story steel building with special moment resisting frame. The results for the case of only the... 

    The Insider Threat: Analyzing and Modeling

    , M.Sc. Thesis Sharif University of Technology Amin, Assiabi (Author) ; Hendesi, Faramarz (Supervisor)
    Abstract
    Nowadays, most of businesses are becoming computer-based. This trend causes the organizations to become more vulnerable to internal and external threats. Internal threats are done through insiders. Insiders unlike outsiders have capabilities which aid them to easily carry out their illicit activities. Unfortunately, most of research in computer security has focused on the outsider threats, whereas the most damaging is the result of insiders’ illicit activities.This dissertation addresses three primary necessities of the research in the area of insider threat: a consistent definition of insider threat, a classification of types of insider threats, and a classification of vulnerabilities which...