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    Optimal exposure detection function for digital and smart-phone camera applications

    , Article Digest of Technical Papers - IEEE International Conference on Consumer Electronics ; 2012 , Pages 149-150 ; 0747668X (ISSN) ; 9781457702310 (ISBN) Yousefi, S ; Rabiee, H. R ; Mianjy, P ; Sharif University of Technology
    2012
    Abstract
    Auto-Exposure detection is a key feature in digital cameras and smart-phones. The image information can be used to detect scene over and under exposure passively. This paper introduces an effective optimal exposure detection function based on joint probability density function of the pixels in the scene  

    Random data and key generation evaluation of some commercial tokens and smart cards

    , Article 2014 11th International ISC Conference on Information Security and Cryptology, ISCISC 2014 ; 2014 , p. 49-54 Boorghany, A ; Sarmadi, S. B ; Yousefi, P ; Gorji, P ; Jalili, R ; Sharif University of Technology
    2014
    Abstract
    In this paper, we report our evaluation of the strength of random number generator and RSA key-pair generator of some commercially available constrained hardware modules, i.e., tokens and smart cards. That was motivated after recent related attacks to RSA public keys, which are generated by constrained network devices and smart cards, and turned out to be insecure due to low-quality randomness. Those attacks are mostly computing pair-wise GCD between the moduli in public keys, and resulted in breaking several thousands of these keys. Our results show that most of the tested hardware modules behave well. However, some have abnormal or weak random generators which seem to be unsuitable for... 

    Investigation of reinforced sic particles percentage on machining force of metal matrix composite

    , Article Modern Applied Science ; Volume 6, Issue 8 , 2012 , Pages 9-20 ; 19131844 (ISSN) Fathipour, M ; Zoghipour, P ; Tarighi, J ; Yousefi, R ; Sharif University of Technology
    MAS  2012
    Abstract
    In this study two-dimensional finite element models of Al/SiC metal matrix composites (MMC) by using of ABAQUS Explicit software are investigated. Chip formations and machining forces for three types of MMC with 5, 15 and 20% of SiC reinforcement particles were studied and compared with experimental data. The resulted chips in simulation and the generated chips in experiments have both continuous and saw tooth in appearance. On the other hand, the variation of the cutting forces with the cutting time in simulation and experiment have fluctuating diagram. This is due to the interaction between cutting tool and SiC particles during chip formation. ABAQUS explicit software was used for... 

    Aperiodic perforated graphene in optical nanocavity absorbers

    , Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 276 , 2022 ; 09215107 (ISSN) Bidmeshkipour, S ; Akhavan, O ; Salami, P ; Yousefi, L ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Aperiodic perforated graphene layers were synthesized and used in fabrication of optical nanocavity absorbers. Chemical vapor deposition-grown graphene (Gr) layers were exposed to oxygen plasma etching to obtain the perforated graphene (pGr). The fabricated pGr/SiO2 (68 nm)/Ag (150 nm) nanocavity could present significant higher optical absorption, especially at around 530 nm wavelength region, as compared to a benchmark Gr/SiO2 (68 nm)/Ag (150 nm) sample. The effect of pore size of the pGr layer on the absorption property of the nanocavity has been studied by both experimental and numerical methods. The dependence of the absorption property of the nanocavity on the incident angles of... 

    Torsional sensitivity and resonant frequency of an AFM with parallel sidewall probes

    , Article Proceedings of the ASME Design Engineering Technical Conference, 15 August 2010 through 18 August 2010, Montreal, QC ; Volume 5 , 2010 , Pages 987-996 ; 9780791844137 (ISBN) Ahmadian, M. T ; Kahrobaiyan, M. H ; Haghighi, P ; Yousefi, A ; Sharif University of Technology
    2010
    Abstract
    The resonant frequencies and torsional sensitivities of an atomic force microscope (AFM) assembled cantilever probe which comprises a horizontal cantilever, two vertical extensions and two tips located at their free ends are studied. This probe makes the AFM capable of measuring, for instance, the outer/inner diameter, roundness and roughness of microstructures like micro-holes and micro nozzles which leads to a time-saving swift scanning process. In this work, the effects of the sample surface contact stiffness and the geometrical parameters such as the ratio of the vertical extension length to the horizontal cantilever length and the distance of the first vertical extension from the... 

    Pyrolytic carbon coating for cytocompatibility of titanium oxide nanoparticles: A promising candidate for medical applications

    , Article Nanotechnology ; Volume 23, Issue 4 , 2012 ; 09574484 (ISSN) Behzadi, S ; Imani, M ; Yousefi, M ; Galinetto, P ; Simchi, A ; Amiri, H ; Stroeve, P ; Mahmoudi, M ; Sharif University of Technology
    2012
    Abstract
    Nanoparticles for biomedical use must be cytocompatible with the biological environment that they are exposed to. Current research has focused on the surface functionalization of nanoparticles by using proteins, polymers, thiols and other organic compounds. Here we show that inorganic nanoparticles such as titanium oxide can be coated by pyrolytic carbon (PyC) and that the coating has cytocompatible properties. Pyrolization and condensation of methane formed a thin layer of pyrolytic carbon on the titanium oxide core. The formation of the PyC shell retards coalescence and sintering of the ceramic phase. Our MTT assay shows that the PyC-coated particles are cytocompatible at employed doses  

    Synthesis and characterization of diopside glass-ceramic matrix composite reinforced with aluminum titanate

    , Article Ceramics International ; Volume 35, Issue 4 , 2009 , Pages 1447-1452 ; 02728842 (ISSN) Yousefi, M ; Alizadeh, P ; Eftekhari Yekta, B ; Molaie, F ; Ghafoorian, N ; Montazerian, M ; Sharif University of Technology
    2009
    Abstract
    Glass-ceramic composites in the SiO2-CaO-MgO-(Na2O) system, reinforced with 5, 10 and 20 wt.% aluminum titanate were synthesized by pressureless sintering. Optimum sintering temperatures with maximum relative density were determined for each composition. The composites were fired above the crystallization peak temperature of glass-ceramic. Mechanical properties of glass-ceramic and sintered composites, such as fracture toughness, flexural strength and Vickers microhardness, were investigated. The sintered composites were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that the composite containing 10... 

    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... 

    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...