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    Improvement of Photocatalytic Efficiency of Nano-Titania Compsites

    , Ph.D. Dissertation Sharif University of Technology Koohestani, Hassan (Author) ; Sadrnezhad, Khatiboleslam (Supervisor)
    Abstract
    Semiconductor-based photo catalysts, titanium dioxide (TiO2) especially, have been extensively studied for the oxidative photo destruction of organic pollutants in wastewaters and hydrogen production as a green energy source. Much effort has been made to remove the restrictions on the use of TiO2 and challenges related to the recovery of powdery photocatalysts. In this study, copper oxide (CuO) and Zirconium oxide (ZrO2) were used to synthesize nanocomposites. Composition of TiO2/CuO and TiO2/ZrO2 with different weight percentages of second dioxide was synthesized by chemical methods and structural properties of samples were studied by X-ray diffraction and scanning electron microscopy.... 

    Simulation of droplet trains in microfluidic networks

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 82, Issue 3 , September , 2010 ; 15393755 (ISSN) Djalali Behzad, M ; Seyed Allaei, H ; Ejtehadi, M. R ; Sharif University of Technology
    2010
    Abstract
    We show that in a microfluidic network with low Reynolds numbers, a system can be irreversible due to hysteresis effects. We simulated a network of pipes that was used in a recent experiment. The network consists of one loop connected to input and output pipes. A train of droplets enters the system at a uniform rate, but the droplets may leave the system in a periodic or even a chaotic pattern. The output pattern depends on the time interval between incoming droplets as well as the network geometry. For some parameters, the system is not reversible  

    Investigation of photocatalytic performance of TiO2 network and fiber geometries

    , Article Desalination and Water Treatment ; Volume 57, Issue 50 , 2016 , Pages 23644-23650 ; 19443994 (ISSN) Koohestani, H ; Sadrnezhaad, S. K ; Kheilnejad, A ; Sharif University of Technology
    Taylor and Francis Inc  2016
    Abstract
    In typical photocatalytic processes slurry reactors are used in which catalyst particles have to be separated from the solution after the process ends which means much higher time and costs. Hence, immobilizing process is carried out on the catalyst to overcome this problem. In this work, fiber and network geometries were produced by particle precipitation on substrates. The obtained structures were characterized by XRD, SEM, and Brunauer–Emmett–Teller analyses. Photocatalytic performance of the samples was investigated by methyl orange degradation and also by hydrogen generation from water/methanol splitting. From the SEM images, the size range of the TiO2 particles in the network... 

    A path-based broadcast algorithm for wormhole hypercubes

    , Article I-SPAN 2009 - The 10th International Symposium on Pervasive Systems, Algorithms, and Networks, 14 December 2009 through 16 December 2009, Kaohsiung ; 2009 , Pages 586-591 ; 9780769539089 (ISBN) Nazi, A ; Sarbazi Azad, H ; Sharif University of Technology
    Abstract
    When implementing some applications in multi-computer systems, broadcast operation is a necessity for efficient communication. Several broadcast algorithms have been proposed in the literature for hypercube networks. In this paper, we evaluate the performance of broadcast routing algorithms for hypercube networks, and propose a new approach by reducing the number of steps required to perform. © 2009 IEEE  

    Adaptive routing in wormhole-switched necklace-cubes: analytical modelling and performance comparison

    , Article Simulation Modelling Practice and Theory ; Volume 17, Issue 9 , 2009 , Pages 1522-1532 ; 1569190X (ISSN) Meraji, S ; Sarbazi Azad, H ; Sharif University of Technology
    2009
    Abstract
    The necklace hypercube has recently been introduced as an attractive alternative to the well-known hypercube. Previous research on this network topology has mainly focused on topological properties, VLSI and algorithmic aspects of this network. Several analytical models have been proposed in the literature for different interconnection networks, as the most cost-effective tools to evaluate the performance merits of such systems. This paper proposes an analytical performance model to predict message latency in wormhole-switched necklace hypercube interconnection networks with fully adaptive routing. The analysis focuses on a fully adaptive routing algorithm which has been shown to be the most... 

    Resource allocation for elastic optical networks using geometric optimization

    , Article Journal of Optical Communications and Networking ; Volume 9, Issue 10 , 2017 , Pages 889-899 ; 19430620 (ISSN) Hadi, M ; Pakravan, M. R ; Sharif University of Technology
    Abstract
    Resource allocation with quality of service constraints is one of the most challenging problems in elastic optical networks that is normally formulated as a mixed-integer nonlinear optimization program. In this paper, we focus on novel properties of geometric optimization and provide a heuristic approach for resource allocation that is much faster than its mixed-integer nonlinear counterpart. Our heuristic consists of two main parts for routing/traffic ordering and power/spectrum assignment. It aims at minimization of the transmit optical power and spectrum usage constrained to the quality of service and physical requirements. We consider three routing and three traffic ordering procedures... 

    Performance comparison of simple regular meshes and their k-ary n-cube variants in optical networks

    , Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 543-550 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) Kianrad, A ; Dadlani, A ; Rajabi, A ; Aghajani, M. R ; Khonsari, A ; Seyed Razi, H ; Sharif University of Technology
    2008
    Abstract
    The need for supporting the ever-growing number of multi-computers in the contemporary Internet has persuaded researches worldwide to search for suitable underlying network topologies with desirable properties. Even in the presence of speedy optical technologies, the arrangement of nodes in a network can be highly influential. Among all the topologies investigated so far, k -ary n-cubes have been reported to be widely adopted in the literature. But in hybrid networks, where the network is composed of a mixture of different types of topologies, the type and size of k-ary n-cubes can greatly affect the performance factor of the network. In this paper, we study and compare the performance...