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    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... 

    Correlation and prediction of small to large sized pharmaceuticals solubility, and crystallization in binary and ternary mixed solvents using the UNIQUAC-SAC model

    , Article Fluid Phase Equilibria ; Volume 519 , 2020 Yousefi Seyf, J ; Asgari, M ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    The recently reported UNIversal QUAsiChemical Segment Activity coefficient (UNIQUAC-SAC) model [developed by Haghtalab and Yousefi Seyf Ind. Eng. Chem. Res. 2015, 54, 8611] provides a practical thermodynamic framework to be used in VLE, LLE, and SLE calculations. The UNIQUAC-SAC model has the advantage of being independent of area (q) and volume (r) structural parameters used in the combinatorial part. While the UNIFAC or UNIFAC-DMD could not apply to the 47% (44 of 94) of the studied molecules because of the undefined groups. Here, the numbers of solvents with identified segment numbers were extended from 82 to 130 with a slight refinement to the previous values. The model parameters... 

    Rank minimization using sums of squares of nonnegative matrices

    , Article 45th IEEE Conference on Decision and Control 2006, CDC, San Diego, CA, 13 December 2006 through 15 December 2006 ; 2006 , Pages 1492-1497 ; 01912216 (ISSN); 1424401712 (ISBN); 9781424401710 (ISBN) Sadati, N ; Isvand Yousefi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    Abstract
    Recently, moment dual approach of sums of squares relaxations developed for polynomial optimization problems was successfully extended to optimization problems with polynomial matrix inequality constraints. In this paper, we first derive an efficient polynomial formulization for matrix rank minimization problem which does not add any slack variable or additional equality or inequality constraint. Using the aforementioned theory, then we propose a hierarchy of convex LMI relaxations to provide a sequence of increasingly tight lower bounds on the global minimum rank of an arbitrary matrix under linear and polynomial matrix inequality constraints. Surprisingly enough, these lower bounds are... 

    Parametrization of PC-SAFT EoS for solvents reviewed for use in pharmaceutical process design: VLE, LLE, VLLE, and SLE Study

    , Article Industrial and Engineering Chemistry Research ; Volume 61, Issue 23 , 2022 , Pages 8252-8268 ; 08885885 (ISSN) Yousefi Seyf, J ; Asgari, M ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    The perturbed chain-statistical associating fluid theory equation of state (PC-SAFT EoS) is one of the state-of-the-art thermodynamic models used in the phase equilibrium calculation of associating mixtures, in particular, in the pharmaceutical industry. Accordingly, parametrization of the PC-SAFT EoS for approved solvents reviewed for use in pharmaceutical process design by the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) was done in the present study. First, the PeC-SAFT EoS model parameters for 41 pure solvents were regressed (of 62 solvents). The available high-quality binary vapor-liquid equilibrium (VLE)... 

    Modeling and control of ionic polymer-metal composite structures

    , Article 13th International Congress on Sound and Vibration 2006, ICSV 2006, Vienna, 2 July 2006 through 6 July 2006 ; Volume 1 , 2006 , Pages 677-681 ; 9781627481502 (ISBN) Yousefi Koma, A ; Fazeli, R ; Sharif University of Technology
    2006
    Abstract
    Robotic devices are traditionally actuated by hydraulic systems or electric motors. However, in compact robotic systems, new actuator technologies are required. Ionic Polymer-Metal Composites (IPMCs) are attractive electroactivc polymer actuators because of their characteristics of large electrically induced bending, mechanical flexibility, low excitation voltage, low density, and ease of fabrication. A dynamic analytical model of IPMC is developed in this study. An RC model is employed based on time response results of a typical silver deposited IPMC. Results show that the electrical model is a suitable presentation of IPMC actuators. The model is tested with two experimental data of IPMC... 

    Characterization of Ss316l Powder Produced by Flame Spraying Method for Additive Manufacturing by Selective Laser Melting by Changing Machine Parameters

    , M.Sc. Thesis Sharif University of Technology Yousefi, Dorsa (Author) ; Sadrnezhaad, Khatiboleslam (Supervisor)
    Abstract
    Selective Laser Melting (SLM) process is a powder-based metal Additive Manufacturing (AM) technique. This developing industry has many advantages like generation of geometrically complex shapes with high density. High Cost, production and characterization of powders, limited material choices and process parameters optimization are some of the challenges associated with SLM. Stainless steel 316L due to its unique properties, like corrosion resistance, high strength, biocompatibility, availability and cost is indeed a commonly used material in SLM. In this research, the characterization of the powder produced by the flame spraying device, which is a new method, was discussed. Wire with 3mm... 

    Modeling and Evaluating Reliability in Wireless Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Yousefi, Hamed (Author) ; Jahangir, Amir Hossein (Supervisor)
    Abstract
    Recent advancement in wireless communications, electronics, low power design and also tendency to use high performance low cost products have led to emergence of Wireless Sensor Networks (WSNs). As the main purpose of a WSN is information gathering and it’s transmission to the sink node, the main problem is to deliver information correctly with minimum energy consumption. Besides, whereas the majority of developed applications for WSNs are event-critical applications, achieving reliable data transfer as the main factor of dependability and quality of service seems vital. However, data transmission is unreliable over multi-hop WSN due to the unreliability of wireless links and node failures. ... 

    Flexibility Analysis in Supply Chain by Using Design Structure Matrix

    , M.Sc. Thesis Sharif University of Technology Yousefi, Zahra (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    Supply chains are socio-technical engineering systems which now days perform in more uncertain operational environment than before. These systems have been vulnerable because of increasing the number of natural disasters, competitiveness and changing the demand. So these systems in order to be survived in such high uncertain environment need to enhance some capabilities in their structure. In this research by considering an assumed auto supply chain, we try to develop an approach to cover uncertainties in operational environment of this system. At the next step, we use design structure matrix modeling to model the interactions between system elements before and after scenario occurring....