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    Dynamic analysis of electrostatically actuated nanobeam based on strain gradient theory

    , Article International Journal of Structural Stability and Dynamics ; Volume 15, Issue 4 , 2014 ; ISSN: 02194554 Miandoab, E. M ; Pishkenari, H. N ; Yousefi Koma, A ; Sharif University of Technology
    2014
    Abstract
    In this study, dynamic response of a micro- and nanobeams under electrostatic actuation is investigated using strain gradient theory. To solve the governing sixth-order partial differential equation, mode shapes and natural frequencies of beam using Euler–Bernoulli and strain gradient theories are derived and then compared with classical theory. Galerkin projection is utilized to convert the partial differential equation to ordinary differential equations representing the system mode shapes. Accuracy of proposed one degree of freedom model is verified by comparing the dynamic response of the electrostatically actuated micro-beam with analogue equation and differential quadrature methods.... 

    Reversible date hiding using multi level integer wavelet decomposition and intelligent coefficient selection

    , Article IEEE International Conference onMultimedia and Expo, ICME 2007, Beijing, 2 July 2007 through 5 July 2007 ; August , 2007 , Pages 2130-2133 ; 1424410177 (ISBN); 9781424410170 (ISBN) Yousef, S ; Rabiee, H. R ; Yousefi, E ; Ghanbari, M ; Sharif University of Technology
    2007
    Abstract
    This paper presents a lossless data hiding method using coefficients of integer wavelet domain. The modification of selected small coefficients of the high frequency subbands are used to embed data. We use the histogram modification to intelligently select the proper coefficients for data hiding. Data embedding is done by processing these selected coefficients. We show that at low payload data hiding our method has comparable PSNR than the best known reversible data hiding techniques, while at higher payloads it has significant superiority on image quality. ©2007 IEEE  

    Experimental study and modelling of saturation molality of NaCl in quaternary aqueous electrolyte solutions at various temperatures

    , Article Desalination ; Volume 267, Issue 2-3 , February , 2011 , Pages 228-232 ; 00119164 (ISSN) Yousefi, L ; Roayaei, E ; Taghikhani, V ; Safekordi, A ; Zahedzadeh, M ; Sharif University of Technology
    2011
    Abstract
    Saturation molality of sodium chloride in mixed aqueous electrolyte solutions containing NaCl, CaSO4 and Na2SO4 was measured at atmospheric pressure over the wide range of temperatures using an equilibrium cell equipped with an accurate temperature control system. The measurements were carried out at different CaSO4 and Na2SO4 concentrations. In order to check the repeatability of the experimental data for the saturation molality of NaCl, the experiments were replicated three times and the values reported were the average of the replicas. To model the data generated in this work, the PDH+UNIFAC-Dortmund activity coefficient model was used. The model used to predict the mean ionic activity... 

    VeriVANca framework: verification of VANETs by property-based message passing of actors in Rebeca with inheritance

    , Article International Journal on Software Tools for Technology Transfer ; Volume 22, Issue 5 , 30 June , 2020 , Pages 617-633 Yousefi, F ; Khamespanah, E ; Gharib, M ; Sirjani, M ; Movaghar, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2020
    Abstract
    Vehicular ad hoc networks have attracted the attention of many researchers during the last years due to the emergence of autonomous vehicles and safety concerns. Most of the frameworks which are proposed for the modeling and analysis VANET applications make use of simulation techniques. Due to the high level of concurrency in these applications, simulation results do not guarantee the correct behavior of the system and more accurate analysis techniques are required. In this paper, we have developed a framework to provide model checking facilities for the analysis of VANET applications. To this end, an actor-based modeling language, Rebeca, is used which is equipped with a variety of model... 

    An optimization based approach embedded in a fuzzy connectivity algorithm for airway tree segmentation

    , Article Proceedings of the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08 - "Personalized Healthcare through Technology", 20 August 2008 through 25 August 2008, Vancouver, BC ; 2008 , Pages 4011-4014 ; 9781424418152 (ISBN) Yousefi Rizi, F ; Ahmadian, A. R ; Fatemizadeh, E ; Alirezaie, J ; Sharif University of Technology
    2008
    Abstract
    The main problem with airway segmentation methods which significantly influences their accuracy is leakage into the extra-luminal regions due to thinness of the airway wall during the process of segmentation. This phenomenon potentially makes large regions of lungparenchyma to be wrongly identified as airways. A solution to this problem in the previous methods was based on leak detection followed by reducing leakage during the segmentation process. This has been dealt with adjusting the segmentation parameters and performing the re-segmentation process on the pre-segmented area. This makes the algorithm very exhaustive and more dependent on the user interaction. The method presented here is... 

    Polysilicon nano-beam model based on modified couple stress and Eringen's nonlocal elasticity theories

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Vol. 63, issue , 2014 , p. 223-228 Miandoab, E. M ; Pishkenari, H. N ; Yousefi-Koma, A ; Hoorzad, H ; Sharif University of Technology
    2014
    Abstract
    In recent years, extensive experiments have shown that classical continuum theory cannot predict the behavior of mechanical microstructures with small size. To accurately design and analyze micro- and nano-electro-mechanical systems, size-dependent continuum theories should be used. These theories model micro- and nano-electro-mechanical systems with higher accuracy because they include size-dependent parameters. In this paper, polysilicon nano-beam is modeled using modified couple stress and Eringen's nonlocal elasticity theories. First, partial differential equations governing the vibration of nano-beams are converted to a one D.O.F. differential equations using Galerkin method, resulting... 

    Electrodepositon of Platinum Nanotubes

    , M.Sc. Thesis Sharif University of Technology Yousefi, Elahe (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Platinum nanotubes were deposited inside the pores of polycarbonate template with the pore size of 200 nm by electrochemical methods. In this regard a solution containing of 0.05 M H2PtCl6 and 0. 1 M H2SO4 in doubly distilled water was utilized. The electrodeposition process was studied by electrochemical techniques such as voltammetry and chronoamperometry methods. It was observed that the process was conducted in several stages including; nucleation and growth in steady state regime. Furthermore, it was concluded that electrodeposition was affected by mass transport restriction and was controlled by a diffusion process. In this regard, all the voltammograms were shifted to more negative... 

    Design of Power Amplifier in Ku Band in the Process of GaAs-pHEMT

    , M.Sc. Thesis Sharif University of Technology Yousefi, Alireza (Author) ; Medi, Ali (Supervisor)
    Abstract
    Power amplifiers are used as the last block of transmitters. This block can be categorized as the one of most important part in communication systems. However, in transmitter systems which require high power to create stable link with the receivers, fabrication process like CMOS are unable to provide such level of power. Thus, designers employ another group of integrated circuits which names MMIC that offers this capability to designers. MMIC is the abbreviation of Microwave Integrated Circuit which is implemented in compound substrates like GaAs. Monolithic microwave integrated circuits enable the implementation of amplifiers in small size, large number, with high precision and appropriate... 

    Wide-band high-efficiency Ku-band power amplifier

    , Article IET Circuits, Devices and Systems ; Vol. 8, issue. 6 , December , 2014 , p. 583-592 ; 1751858X Yousefi, A ; Medi, A ; Sharif University of Technology
    2014
    Abstract
    A 37 dBm power amplifier (PA) is designed on a 0.25 μm optical T-gate pseudomorphic high electron mobility transistor (pHEMT) technology. The design of this two-stage PA along with a step-by-step design procedure is presented in this paper. This methodology can be used for design of PA in different technologies and frequencies. The PA delivers 5 W output power over the frequency band of 13-19 GHz. It shows average power-added efficiency of 37% and large signal gain of 15 dB in measurements which is consistent with simulation results. The output power and efficiency of the realised amplifier reach maximums of 37.6 dBm and 45%, respectively. Considering output power, bandwidth, chip area and... 

    A Comparison between Virtual Private LAN Service (VPLS)and P2MP IP-only LAN Service (IPLS)

    , M.Sc. Thesis Sharif University of Technology Yousefi, Dariush (Author) ; Ajorloo, Hossein (Supervisor)
    Abstract
    Today Ethernet is the predominant technology for implementing Local Area Networks. Its privileges encourage service providers to extend Ethernet from Local Area Networks to Metropolitan Area Networks or even Wide Area Networks. Ethernet benefits such as low operational costs, well interoperability, plug-n-paly characteristic and rapid provisioning on demand make Ethernet ideal for Metropolitan Area Networks.But Ethernet by itself has some weakness like flat structure that makes it unfit for use in Metropolitan Area Networks. A suitable solution for taking advantages of Ethernet benefits in service provider network is using Ethernet in access network and applying multi-point to multi-point... 

    Effects of free quartz on mechanical behaviour of kaolinite based geopolymers

    , Article Materials Technology ; Volume 26, Issue 2 , Jul , 2011 , Pages 96-99 ; 10667857 (ISSN) Yousefi, E ; Majidi, B ; Sharif University of Technology
    2011
    Abstract
    Quartz is usually detected as an impurity of kaolinite clays. The present work attempts to evaluate the role and behaviour of quartz particles in geopolymerisation and its probable effects on mechanical behaviour of geopolymeric products. Two kaolinite clays with different free quartz contents were used as raw materials to produce geopolymers. Results showed that using high content quartz kaolin causes higher compressive strength. Scanning electron microscopy studies confirmed that quartz does not participate in geopolymerisation and completely remains in the structure as fine particles. High hardness quartz particles by retarding crack growth in the geopolymer matrix enhance mechanical... 

    investigation of the Effect of Piezo-Electric Patch on the Modal Properties and Flutter Speed of Turbomachine Blade

    , M.Sc. Thesis Sharif University of Technology Yousefi, Masoud (Author) ; Haddadpour, Hassan (Supervisor)
    Abstract
    In order to investigaton of dynamics behavior and determination of the aeroelastic stability of the turbomachine blade. the turbomachine blade is modeled by using the beam model, taking into account all degrees of freedom, the effect of warping, rotation and seting angle. For aerodynamic modeling, the Smith and Whitehead models are used which are valid in subsonic flow. The validity of the derived formulation is confirmed through comparison with those obtained from the finite element software and the available results in the literature. Then, by using the state feedback controller, the effect of sensor and piezoelectric actuator on the vibrations reduction of the structure and increasing the... 

    A Task-Based Greedy Scheduling Algorithm for Minimizing Energy of MapReduce Jobs

    , Article Journal of Grid Computing ; Volume 16, Issue 4 , 2018 , Pages 535-551 ; 15707873 (ISSN) Yousefi, M.H.N ; Goudarzi, M ; Sharif University of Technology
    Springer Netherlands  2018
    Abstract
    MapReduce and its open source implementation, Hadoop, have gained widespread adoption for parallel processing of big data jobs. Since the number of such big data jobs is also rapidly rising, reducing their energy consumption is increasingly more important to reduce environmental impact as well as operational costs. Prior work by Mashayekhy et al. (IEEE Trans. Parallel Distributed Syst. 26, 2720–2733, 2016), has tackled the problem of energy-aware scheduling of a single MapReduce job but we provide a far more efficient heuristic in this paper. We first model the problem as an Integer Linear Program to find the optimal solution using ILP solvers. Then we present a task-based greedy scheduling... 

    A Framework for Formal Analysis of Warning Message Dissemination Schemes in VANETs Using an Extension of Rebeca

    , M.Sc. Thesis Sharif University of Technology Yousefi, Farnaz (Author) ; Movaghar, Ali (Supervisor)
    Abstract
    Vehicular ad-hoc networks have attracted the attention of many researchers during the last years due to the emergence of autonomous vehicles and the safety concerns regarding their use in near future. One of the major applications in this domain is the usage of vehicle to vehicle communication for warning message dissemination in dangerous situations to prevent more damage. A number of schemes have been proposed regarding the selection of forwarding nodes in this application and there is a need for developing frameworks for analysis and comparison of the schemes in fair situation. Most of the proposed frameworks make use of simulation techniques for the analysis of schemes. However, due to... 

    Optimal Model of Industrial Waste Heat Application in Desalination System: A Case Study of Hormozgan Province

    , M.Sc. Thesis Sharif University of Technology Yousefi, Paria (Author) ; Avami, Akram (Supervisor)
    Abstract
    Increasing population growth and scarcity of fresh water resources have created the challenge of water supply, especially in the Mena region. Thus, many countries in the region have turned to innovation in the development of high-energy seawater desalination technologies. Utilizing the waste heat of refineries in the desalination industry can reduce costs and preserve the environment. In this article, effective ways to use the waste heat of other flue recovery steam of Bandar Abbas oil refinery are investigated. The integration of the heat recovery system consisting of recuperative heat exchangers and heat pipes with thermal desalination plants is investigated by multi-stage flash and... 

    Optimization of the Pulp and Paper Mill Wastewater Treatment System from Recycling with the Aim of Reducing COD by Conducting a Laboratory Pilot Plant

    , M.Sc. Thesis Sharif University of Technology Yousefi, Farid (Author) ; Raie, Mohammad (Supervisor)
    Abstract
    Paper and cardboard waste pulping consume large volumes of water, so the discharge of this effluent without proper treatment can have far-reaching environmental consequences. The color and variable COD concentration of wastewater in this industry make treating this wastewater complicated. Therefore, this study aims to reduce the COD of the wastewater treatment plant of a pulp and paper mill under different laboratory conditions to achieve environmental standards in Iran.In this study, coagulation-flocculation and the Fenton process on the wastewater entering the treatment plant were investigated first. It was found that coagulation and flocculation by 750-1250 ppm of alum coagulant and ten... 

    A hybrid fuzzy based algorithm for 3D human airway segmentation

    , Article 2nd International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2008, Shanghai, 16 May 2008 through 18 May 2008 ; 2008 , Pages 2295-2298 ; 9781424417483 (ISBN) Yousefi Rizi, F ; Ahmadian, A ; Sahba, N ; Tavakoli, V ; Alirezaie, J ; Fatemizadeh, E ; Rezaie, N ; Sharif University of Technology
    IEEE Computer Society  2008
    Abstract
    Segmentation of the human airway tree from volumetric computed tomography images is an important stage for many clinical applications such as virtual bronchoscopy. The main challenges of previously developed methods are to deal with two problems namely, leaking into the surrounding lung parenchyma during segmentation and the need to manually adjust the parameters. To overcome these problems, a multi-seeded fuzzy based region growing approach in conjuction with the spatial information of voxels is proposed. Comparison with a commonly used region growing segmentation algorithm shows that the proposed method retrieves more accurate results by achieving the specificity and sensitivity of 98.81%... 

    Efficient and practical protocol for silylation of hydroxyl groups using reusable lithium perchlorate dispread in silica gel under neutral condition [electronic resource]

    , Article Journal of Organometallic Chemistry ; 2006, Volume 691, Issue 5, Pages 817–820 Azizi, N. (Najmodin) ; Yousefi, R ; Saidi, M. R ; Sharif University of Technology
    Abstract
    A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups  

    Analyses of Effect of Bank Branching on Deposit Market Share and Market Size in Iran Banking Industry

    , M.Sc. Thesis Sharif University of Technology Yousefi, Fateme (Author) ; Fatemi, Farshad (Supervisor)
    Abstract
    This thesis aim to the study of the effect of bank’s branching decisions on deposit market. Using panel data banks from Iran, we study effect of branching on market share and market size. In theoretical part, we assume that banks maximize discounted flow of the profits. We also assume that the banks take into account the reaction from rival banks in setting number of branches. Banks are assumed to expect the rival banks react by a lag of one period. In empirical part, in order to distinguish between aggregate market size effect and market share effect, we rewrite quantity of deposit in banks as the product of aggregate deposit and market share. We specify deposit market share function with... 

    Statistical analysis for enzymatic decolorization of acid orange 7 by Coprinus cinereus peroxidase

    , Article International Biodeterioration and Biodegradation ; Volume 64, Issue 3 , 2010 , Pages 245-252 ; 09648305 (ISSN) Yousefi, V ; Kariminia, H. R ; Sharif University of Technology
    2010
    Abstract
    Enzymatic decolorization of the monoazo dye, acid orange 7 (AO7) by the fungal peroxidase from Coprinus cinereus NBRC 30628 is a complex system, which is greatly affected by temperature, pH, enzyme activity and the concentrations of H2O2 and dye concentration. The study of these factors and investigating the combined interactions between them by applying one-factor-at-a-time (OFAT) method and two other statistical methods including 2-factorial method and response surface methodology (RSM) were aimed in this work. Through OFAT analysis the optimized conditions were a temperature of 25 °C, pH 9.0 with H2O2 concentration of about 3.9 mM and AO7 concentration of 40 mg/l. A complete...