Search for: termination
0.006 seconds

    Evaluation of Exerted Drag Force on Alkane Saturated Air Bubbles in Aqueous Solutions by Experimental Studies

    , M.Sc. Thesis Sharif University of Technology Rajabzadeh Dezfuli, Mehdi (Author) ; Bastani, Dariush (Supervisor) ; Lotfi, Marzieh (Supervisor)
    Interfacial phenomena and properties of interphase surfaces in dynamic mode play an important role in industrial processes that include gas-liquid and liquid-liquid multiphase flows. As well as, interface knowledge leads to better understanding of natural and fundamental phenomena. The present study has been performed for understanding about dynamic behavior of interphase surfaces in the presence of nanoparticles and hexane vapor in gas-liquid dispersion systems. In this research, rising bubble method has been used as one of the most conventional techniques. Accordingly, aqueous solutions of nanosilica were prepared in concentrations of 50, 100, 200, 400 and 1200 ppm as continuous phase... 

    Combination of Linear MPC and Differential Game Theory for Optimal Cooperative Terminal Guidance Law with HIL Simulation

    , M.Sc. Thesis Sharif University of Technology Akbari, Mohammad Sadegh (Author) ; Nobahari, Hadi (Supervisor)
    In this research, a cooperative terminal guidance algorithm has been derived for simultaneous multi-interceptor collision with a target. This algorithm is obtained using the combination of model predictive control method and differential game theory. One of the features of this method is the calculation of the optimal guidance command in the form of an explicit relationship. Another feature of this method is its resistance to disturbances due to the use of differential game theory. The first innovation of this research is the use of this hybrid method to create a guidance algorithm, even in the non-cooperative guidance problem. The next innovation is in creating a cooperative terminal... 

    A harmonic termination technique for single-and multi-band high-efficiency class-F MMIC power amplifiers

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 62, Issue 5 , May , 2014 , Pages 1212-1220 ; ISSN: 00189480 Nikandish, G ; Babakrpur, E ; Medi, A ; Sharif University of Technology
    This paper presents a harmonic termination technique for single-and multi-band high-efficiency class-F monolithic microwave integrated circuit (MMIC) power amplifiers (PAs). The harmonic termination network (HTN), realized with the minimum possible number of elements, can be used to terminate an arbitrary number of harmonics in a single-band PA or harmonics of multiple frequencies in a concurrent multi-band PA. The drain and gate bias lines are embedded in the HTNs to obviate the need for RF chokes and reduce the chip area. A single-and a dual-band MMIC PA are designed using the proposed technique and implemented in a 0.25-μm AlGaAs-InGaAs pHEMT technology. The single-band 5.5-GHz PA... 

    A new efficient approach to search for all multi-state minimal cuts

    , Article IEEE Transactions on Reliability ; Volume 63, Issue 1 , March , 2014 , Pages 154-166 Forghani Elahabad, M ; Mahdavi Amiri, N ; Sharif University of Technology
    There are several exact or approximating approaches that apply {m d}-MinCuts (d-MCs) to compute multistate two-Terminal reliability. Searching for and determining d-MCs in a stochastic-flow network are important for computing system reliability. Here, by investigating the existing methods and using our new results, an efficient algorithm is proposed to find all the d-MCs. The complexity of the new algorithm illustrates its efficiency in comparison with other existing algorithms. Two examples are worked out to show how the algorithm determines all the d -MCs in a network flow with unreliable nodes, and in a network flow of moderate size. Moreover, using the d-MCs found by the algorithm, the... 

    Pd(OAc)2 without added ligand as an active catalyst for Mizoroki-Heck reaction in aqueous media

    , Article RSC Advances ; Volume 2, Issue 32 , 2012 , Pages 12091-12095 ; 20462069 (ISSN) Amini, M ; Bagherzadeh, M ; Moradi Shoeili, Z ; Boghaei, D. M ; Sharif University of Technology
    Conditions for an efficient ligand-free Heck C-C coupling reaction of aryl iodides and bromides with terminal olefins under aerobic conditions have been developed. Critical to the success of this new protocol is the use of palladium acetate as an extremely active catalyst for the Heck reaction in water and aqueous media. Both the base and the solvent were found to have a fundamental influence on the efficiency of the reaction, with K2CO3 and a mixture of (2:1) H2O/DMSO being the optimal base and solvent, respectively  

    Bus network design using genetic algorithm

    , Article 53rd Annual Transportation Research Forum, TRF 2012, 15 March 2012 through 17 March 2012, Tampa, FL ; Volume 1 , 2012 , Pages 210-225 ; 9781622764037 (ISBN) Sadrsadat, H ; Poorzahedi, H ; Haghani, A ; Sharifi, E ; Sharif University of Technology
    The bus network design problem is an important problem in transportation planning. It is the problem of determining a network of bus lines which best achieves a predetermined objective. This may be done with or without the presence of rapid transit lines. This study is devoted to solving this problem using genetic algorithm. The fitness function is defined as the benefit to the users of the bus network less the cost of the operator of the network, which is to be maximized subject to constraints that properly distribute bus routes over the study area. Objective function calculation depends on the basic data of the city and its bus lines and does not need traffic assignment results. So, it is... 

    Use of a novel initiator for synthesis of amino-end functionalized polystyrene (NH 2-PS) by atom transfer radical polymerization

    , Article Journal of Polymer Research ; Volume 19, Issue 1 , January , 2012 ; 10229760 (ISSN) Pourjavadi, A ; Seidi, F ; Jahromi, P. E ; Salimi, H ; Roshan, S ; Najafi, A ; Bruns, N ; Sharif University of Technology
    Here we report a versatile new method for endfunctionalizing polystyrene. In order to produce polystyrene with an amino end group, 2-(3-bromo-3- phenylpropyl) isoindoline-1,3-dione was synthesized and used as a novel initiator for ATRP. After ATRP polymerization, tri-n-butyltin hydride ((n-Bu) 3SnH) reductively replace existing halogens on polymer chains by hydrogen. Finally, the phthaloyl groups on polymer backbone were cleaved by treatment with hydrazine yielding amino terminated polystyrene. A polymer with M n≈10,350 and M w/M n01.17 was obtained. Therefore, this method allows the preparation of amino end functionalized polystyrene of narrow polydispersity with complete degree of... 

    Embryonic stem cells maintain an undifferentiated state on dendrimer-immobilized surface with D-glucose display

    , Article Polymers ; Volume 3, Issue 4 , 2011 , Pages 2078-2087 ; 20734360 (ISSN) Mashayekhan, S ; Kim, M. H ; Kino Oka, M ; Miyazaki, J. I ; Taya, M ; Sharif University of Technology
    In serial passaging cultures of mouse embryonic stem (ES) cells, we employed a dendrimer-immobilized substrate that displayed D-glucose as a terminal ligand. The D-glucose-displaying dendrimer (GLU/D) surface caused the ES cells to form loosely attached spherical colonies, while those on a gelatin-coated surface formed flatter colonies that were firmly attached to the surface. Despite the morphological similarities between the colonies on the GLU/D surface and aggregates on a conventional bacteriological dish, immunostaining and RT-PCR analyses revealed the maintenance of cells within the spherical colonies on the GLU/D surface in an undifferentiated state with very low expressions of... 

    Cellulose-immobilized NHC-Cu(i) complex: An efficient and reusable catalyst for multicomponent synthesis of 1,2,3-triazoles

    , Article RSC Advances ; Volume 5, Issue 120 , Nov , 2015 , Pages 99498-99501 ; 20462069 (ISSN) Pourjavadi, A ; Habibi, Z ; Sharif University of Technology
    Royal Society of Chemistry  2015
    A novel cellulose supported copper NHC complex has been prepared by the reaction of cellulose supported imidazolium salt with copper(i) iodide. The catalyst is active in the synthesis of 1,2,3-triazoles via a one-pot reaction of alkyl/benzyl halides or tosylates and terminal alkynes, with sodium azide in water  

    A new method for design of fixed wing micro air vehicle

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 229, Issue 5 , April , 2015 , Pages 837-850 ; 09544100 (ISSN) Hassanalian, M ; Khaki, H ; Khosravi, M ; Sharif University of Technology
    SAGE Publications Ltd  2015
    This study attempts to present a new and comprehensive cycle for the design of fixed wing micro air vehicles. The idea is to propose a complete cycle containing all micro air vehicles design subjects such as aerodynamics, stability, structure, and navigation. The main aim of the cycle is to decrease the designing time for an optimum design. In this method, the sizing process is started simultaneously, which involves the following cases: specification of mission and aviation plan; determination of planform and aspect ratio; constraint analysis; estimation of plane weight. Completion of these four phases results in the specification of the geometry and dimensions of the wing in an optimum... 

    Estimating terminal velocity of rough cracks in the framework of discrete fractal fracture mechanics

    , Article Engineering Fracture Mechanics ; Volume 77, Issue 10 , 2010 , Pages 1516-1526 ; 00137944 (ISSN) Yavari, A ; Khezrzadeh, H ; Sharif University of Technology
    In this paper we first obtain the order of stress singularity for a dynamically propagating self-affine fractal crack. We then show that there is always an upper bound to roughness, i.e. a propagating fractal crack reaches a terminal roughness. We then study the phenomenon of reaching a terminal velocity. Assuming that propagation of a fractal crack is discrete, we predict its terminal velocity using an asymptotic energy balance argument. In particular, we show that the limiting crack speed is a material-dependent fraction of the corresponding Rayleigh wave speed  

    A robust finite-time hyperchaotic secure communication scheme based on terminal sliding mode control

    , Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 854-858 ; 9781467387897 (ISBN) Abooee, A ; Moravej Khorasani, M ; Haeri, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    In this paper, a new robust finite-time hyperchaotic secure communication scheme is proposed by combining robust finite-time synchronization of two hyperchaotic systems and hyperchaotic multiplication masking technique. The mentioned synchronization is achieved by introducing new terminal sliding mode controllers. As a main novelty of the introduced scheme, an adjustable total finite time is obtained such that the decrypted message signal will be completely identical with the transmitted message signal for times larger than the discussed finite time. Compared with other secure communication schemes, the suggested method has several advantages including finite-time stability for dynamical... 

    Multi-party secret key agreement over state-dependent wireless broadcast channels

    , Article IEEE Transactions on Information Forensics and Security ; Volume PP, Issue 99 , 2016 ; 15566013 (ISSN) Jafari Siavoshani, M ; Mishra, S ; Fragouli, C ; Diggavi, S. N ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    We consider a group of m trusted and authenticated nodes that aim to create a shared secret key K over a wireless channel in the presence of an eavesdropper Eve. We assume that there exists a state dependent wireless broadcast channel from one of the honest nodes to the rest of them including Eve. All of the trusted nodes can also discuss over a cost-free, noiseless and unlimited rate public channel which is also overheard by Eve. For this setup, we develop an information-theoretically secure secret key agreement protocol. We show the optimality of this protocol for "linear deterministic" wireless broadcast channels. This model generalizes the packet erasure model studied in literature for... 

    Hybridizations of genetic algorithms and neighborhood search metaheuristics for fuzzy bus terminal location problems

    , Article Applied Soft Computing Journal ; Volume 46 , 2016 , Pages 220-229 ; 15684946 (ISSN) Babaie Kafaki, S ; Ghanbari, R ; Mahdavi Amiri, N ; Sharif University of Technology
    Elsevier Ltd 
    We propose modified hybridizations of genetic algorithms with some neighborhood search based metaheuristics. In our hybrid algorithms, we consider gradually increasing probability for the application of the neighborhood search procedure on the best individuals as the number of iterations of the genetic algorithm increases. We implement the proposed hybrid algorithms and compare their performance with two other recently proposed hybrid algorithms which, in contrast, use the neighborhood search procedure on all the individuals of the population, two hybrid algorithms applying simulated annealing on the best individual in the papulation in every iteration and three non-hybrid metaheuristic... 

    Collaboration alignment in distributed interference management in uplink cellular systems

    , Article 2016 IEEE International Symposium on Information Theory, 10 July 2016 through 15 July 2016 ; Volume 2016-August , 2016 , Pages 1456-1460 ; 21578095 (ISSN) ; 9781509018062 (ISBN) Kananian, B ; Maddah Ali, M. A ; Shariatpanahi, S. P ; Khalaj, B. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    We consider a cellular wireless system including several interfering multi-user multi-antenna uplink channels, where the base station of each cell has to locally recover the messages of its corresponding users. We use a linear Wyner model, where each base station experiences interference only from the users in the two neighboring cells. Each base station is connected to the two nearby base stations through a backhaul link. The objective is to achieve the maximum degrees of freedom per cell, with minimum aggregated load in the backhaul. We propose a successive cooperative alignment scheme, in which each base station forms backhaul messages by combining the previous received backhaul messages... 

    Multicast beamformer design for coded caching

    , Article IEEE International Symposium on Information Theory - Proceedings, 17 June 2018 through 22 June 2018 ; Volume 2018-June , 2018 , Pages 1914-1918 ; 21578095 (ISSN) ; 9781538647806 (ISBN) Tolli, A ; Shariatpanahi, S. P ; Kaleva, J ; Khalaj, B ; Sharif University of Technology
    A single cell downlink scenario is considered where a multiple-antenna base station delivers contents to cache-enabled user terminals. Using the ideas from multi-server coded caching (CC) scheme developed for wired networks, a joint design of CC and general multicast beamforming is considered to benefit from spatial multiplexing gain, improved interference management and the global CC gain, simultaneously. The proposed multicast beamforming strategies utilize the multiantenna multicasting opportunities provided by the CC technique and optimally balance the detrimental impact of both noise and inter-stream interference from coded messages transmitted in parallel. The proposed scheme is shown... 

    Investigation of the impact of synthesized hydrophobic magnetite nanoparticles on mass transfer and hydrodynamics of stagnant and stirred liquid–liquid extraction systems

    , Article Chemical Engineering Research and Design ; Volume 147 , 2019 , Pages 305-318 ; 02638762 (ISSN) Hatami, A ; Azizi, Z ; Bastani, D ; Sharif University of Technology
    Institution of Chemical Engineers  2019
    The impact of modified magnetite nanoparticles (MMNPs)on hydrodynamics and mass transfer in liquid–liquid extraction process was assessed using a ternary chemical system of toluene-acetic acid–water. The organic phase which contained toluene and acetic acid was dispersed through water, and the mass transfer of acetic acid between two phases was investigated. The hydrophobic modified magnetite nanoparticles (MMNPs)prepared through an optimized in-situ method were added to the dispersed phase at different concentrations (0.001−0.005 wt%). Two separate conditions were provided in the experiments, i.e. stagnant and stirred continuous phase. The latter case was provided by a rotor at two... 

    A reliable and fast response buck converter based on interleaved converter

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 804-807 ; 9781728115085 (ISBN) Keshtkar Teeula, A ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Power Distribution Unit (PDU) is a power supply unit that supplies various DC voltage levels for electric equipment. Reliability of PDU is very important in electrical systems. Buck converter is frequently used in PDU to provide the lower voltage levels than the source voltage level. The output capacitor of the buck converter is the main factor of failure. In this paper, we present a method to design a buck converter with almost no inductor current ripple. If the inductor current ripple is eliminated, the output capacitor can be removed from the converter. By removing the capacitor, the reliability and transient response of the converter can be improved considerably. The proposed method is... 

    Distributed voting in beep model

    , Article Signal Processing ; Volume 177 , 2020 Ghojogh, B ; Salehkaleybar, S ; Sharif University of Technology
    Elsevier B.V  2020
    We consider the problem of distributed multi-choice voting in a setting that each node can communicate with its neighbors merely by sending beep signals. Given its simplicity, the beep communication model is of practical importance in different applications such as system biology and wireless sensor networks. Yet, the distributed majority voting has not been resolved in this setting. In this paper, we propose two algorithms, named Distributed Voting with Beeps, to resolve this problem. In the first proposed algorithm, the adjacent nodes having the same value form a set called spot. Afterwards, the spots with majority value try to corrode the spots with non-majority values. The second... 

    Design of nanoswitch based on C20-bowl molecules: a first principles study

    , Article Microelectronics Journal ; Volume 39, Issue 12 , 2008 , Pages 1499-1503 ; 00262692 (ISSN) Ganji, M. D ; Aghaei, H ; Gholami, M. R ; Sharif University of Technology
    We demonstrate theoretically by density functional non-equilibrium Green's function method that a much simplest two-terminal wire can exhibit switching, and we present a realistic theory of its behavior. We consider a C20-bowl molecular wire sandwiched between an Au (1 0 0) substrate and a monatomic Au scanning tunneling microscope (STM) tip. Lateral motion of the tip over the pentagon ring causes it to change from one conformation class to the other and to switch between a strongly and a weakly conducting state. Thus, surprisingly, despite their apparent simplicity, these Au/C20/Au nanowires are shown to be a convenient switch, the simplest two-terminal molecular switches to date....