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    Cooperative hybrid ARQ in solar powered wireless sensor networks

    , Article Microelectronics Reliability ; Volume 52, Issue 12 , 2012 , Pages 3043-3052 ; 00262714 (ISSN) Jalali, F ; Khodadoustan, S ; Ejlali, A ; Sharif University of Technology
    2012
    Abstract
    Energy harvesters are used in today's Wireless Sensor Networks (WSNs) to harvest energy from the environment. Although an energy harvester can provide a supply source with a much greater lifetime than a battery, the amount of available energy for an energy harvesting system is a random variable. Furthermore, the proper management of energy harvesters has a considerable impact on reliability. It has been observed that cooperative error control mechanisms like Cooperative Automatic Repeat Request (C-ARQ) and Cooperative Hybrid ARQ (C-HARQ) can be used for improving the energy management and reliability in Energy Harvesting WSNs (EH-WSNs). Recently, the impact of C-ARC mechanism has been... 

    Dye-sensitized solar cells based on a single layer deposition of TiO 2 from a new formulation paste and their photovoltaic performance

    , Article Solar Energy ; Volume 86, Issue 9 , 2012 , Pages 2654-2664 ; 0038092X (ISSN) Mohammadi, M. R ; Louca, R. R. M ; Fray, D. J ; Welland, M. E ; Sharif University of Technology
    Abstract
    A new strategy for enhancing the efficiency and reducing the production cost of TiO 2 solar cells by design of a new formulated TiO 2 paste with tailored crystal structure and morphology is reported. The conventional three- or four-fold layer deposition process was eliminated and replaced by a single layer deposition of TiO 2 compound. Different TiO 2 pastes with various crystal structures, morphologies and crystallite sizes were prepared by an aqueous particulate sol-gel process. Based on simultaneous differential thermal (SDT) analysis the minimum annealing temperature to obtain organic-free TiO 2 paste was determined at 400°C, being one of the lowest crystallization temperatures of TiO 2... 

    Nonlinear adaptive control of grid-connected three-phase inverters for renewable energy applications

    , Article International Journal of Control ; 2015 ; 00207179 (ISSN) Mahdian Dehkordi, N ; Namvar, M ; Karimi, H ; Piya, P ; Karimi Ghartemani, M ; Sharif University of Technology
    Abstract
    Distributed generation (DG) units are often interfaced to the main grid using power electronic converters including voltage-source converters (VSCs). A VSC offers dc/ac power conversion, high controllability, and fast dynamic response. Because of nonlinearities, uncertainties, and system parameters’ changes involved in the nature of a grid-connected renewable DG system, conventional linear control methods cannot completely and efficiently address all control objectives. In this paper, a nonlinear adaptive control scheme based on adaptive backstepping strategy is presented to control the operation of a grid-connected renewable DG unit. As compared to the popular vector control technique, the... 

    Year-round outdoor experiments on a multi-stage active solar still with different numbers of solar collectors

    , Article Applied Energy ; Volume 152 , 2015 , Pages 39-46 ; 03062619 (ISSN) Feilizadeh, M ; Karimi Estahbanati, M. R ; Jafarpur, K ; Roostaazad, R ; Feilizadeh, M ; Taghvaei, H ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract
    The present work investigated the outdoor performance of a basin type multi-stage solar still as well as the effect of collector over basin area (CBA) ratio on the distillate production. The effect of CBA was studied in outdoor experiments for the first time. The system consisted of a still coupled with one, two or three flat-plate solar collectors. In order to study the effect of CBA more accurately, the experiments were conducted in both winter and summer. In these experiments, the distilled water production of the multi-stage still was measured during the whole 24. h of a day on an hourly basis. The results revealed that in the winter, the basin coupled to one solar collector (CBA. =... 

    Efficient dye-sensitized solar cells based on carbon-doped TiO2 hollow spheres and nanoparticles

    , Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 11 , 2015 , Pages 8863-8876 ; 09574522 (ISSN) Tabari Saadi, Y ; Mohammadi, M. R ; Sharif University of Technology
    Springer New York LLC  2015
    Abstract
    Different structures of TiO2 photoelectrodes are fabricated with various arrangement modes of the layers. TiO2 nanoparticles, synthesized by stabilizing agent free non-hydrolytic sol–gel method, are employed as the under layer, whereas carbon-doped TiO2 hollow spheres, prepared by hydrothermally grown carbon template, are used as the scattering layer of solar cells. The nanoparticles (22 nm) have anatase structure, while 300–700 nm hollow spheres show mixtures of anatase and rutile phases. X-ray photoelectron spectroscopy confirms that carbon is doped into TiO2 hollow spheres, resulting in a decrease in band gap energy in the range 2.96–3.13 eV compared with 3.04 eV band gap energy for the... 

    Nitrogen-doped submicron-size TiO2 particles as bifunctional light scatterers in dye-sensitized solar cells

    , Article Applied Physics A: Materials Science and Processing ; Volume 119, Issue 4 , 2015 , Pages 1283-1290 ; 09478396 (ISSN) Shogh, S ; Mohammadpour, R ; Iraji zad, A ; Taghavinia, N ; Sharif University of Technology
    Springer Verlag  2015
    Abstract
    The structural, electrical, optical, and photovoltaic properties of aggregated submicron nitrogen-doped TiO2 particles (NTiO2) and the influence of utilizing them, in comparison with undoped ones, as the light-scattering layer of dye-sensitized solar cells were investigated. Field emission scanning electron microscope, X-ray diffraction, and diffuse reflectance spectra showed that both type samples have similar morphology, crystal phase, and scattering feature. Moreover, photoluminescence, Mott–Schottkey, and photovoltaic characteristics such as IMPS/IMVS and charge extraction analysis indicated that the NTiO2 layer is an efficient scatterer in two aspects: enhancement of light-harvesting... 

    Development of the energy hub networks based on distributed energy technologies

    , Article Simulation Series, 26 July 2015 through 29 July 2015 ; Volume 47, Issue 10 , 2015 , Pages 216-223 ; 07359276 (ISSN) Maroufmashat, A ; Elkamel, A ; Sattari Khavas, S ; Fowler, M ; Roshandel, R ; Elsholkami, M ; Sharif University of Technology
    The Society for Modeling and Simulation International  2015
    Abstract
    In this paper the creation of multiple energy hubs that make up a complex energy network are modeled and optimized for a selection of six scenarios to examine both their financial viability and potential reduction of greenhouse gas emissions. As a proposed case study scenario for the model, three energy hubs are considered: a 'residential complex (RC)', a 'commercial shopping plaza (CS)', and a 'school (S)'. The use of combined heat and power systems, solar photovoltaic, solar collectors and network interaction are also examined for their impact on efficiency and cost. The modeling is undertaken and carried out by General Algebraic Modeling System (GAMS). It is shown that cost can be reduced... 

    The impact of climate condition on the optimal size of direct coupled photovoltaic-electrolyzer systems

    , Article Simulation Series, 26 July 2015 through 29 July 2015 ; Volume 47, Issue 10 , July , 2015 , Pages 224-229 ; 07359276 (ISSN) Sayedin, F ; Maroufmashat, A ; Sattari khavas S ; Elkamel, A ; Aladwani, S ; Sharif University of Technology
    The Society for Modeling and Simulation International  2015
    Abstract
    Solar energy exists extensively in all parts of the world. However the intermittency of solar energy presents critical challenges to PV system. The intermittency can be covered by storing solar energy in chemical bonds such as hydrogen. This process can be performed by photovoltaic powered electrolysis of water. The energy transfer efficiency between PV and electrolyzer is subject to the distance between maximum power points (MPP) of PV module and operating points. The operating points can be adjusted by optimizing the design parameters of the electrolyzer but the maximum power points are function of PV module characteristics, solar radiation and ambient temperature. Therefore the weather... 

    A novel thermo-photovoltaic cell with quantum-well for high open circuit voltage

    , Article Superlattices and Microstructures ; Volume 83 , July , 2015 , Pages 61-70 ; 07496036 (ISSN) Kouhsari, E. S ; Faez, R ; Akbari Eshkalak, M ; Sharif University of Technology
    Academic Press  2015
    Abstract
    Abstract We design a thermo-photovoltaic Tandem cell which produces high open circuit voltage (Voc) that causes to increase efficiency (η). The currently used materials (AlAsSb-InGaSb/InAsSb) have thermo-photovoltaic (TPV) property which can be a p-n junction of a solar cell, but they have low bandgap energy which is the reason for lower open circuit voltage. In this paper, in the bottom cell of the Tandem, there is 30 quantum wells which increase absorption coefficients and quantum efficiency (QE) that causes to increase current. By increasing the current of the bottom cell, the top cell thickness must be increased because the top cell and the bottom cell should have the same current. In... 

    Plasmonic effects of infiltrated silver nanoparticles inside TiO2 film: Enhanced photovoltaic performance in DSSCs

    , Article Journal of the American Ceramic Society ; Volume 99, Issue 1 , 2016 , Pages 167-173 ; 00027820 (ISSN) Andaji Garmaroudi, Z ; Mohammadi, M. R ; Sharif University of Technology
    Blackwell Publishing Inc 
    Abstract
    The plasmonic effects of infiltrated silver (Ag) nanoparticles, with different contents, inside a nanostructured TiO2 film on the photovoltaic performance of dye-sensitized solar cells (DSSCs) are explored. The synthesized Ag nanoparticles are immobilized onto deposited TiO2 nanoparticles by a new strategy using 3-mercaptopropionic acid (MPA), a bifunctional linker molecule. Transmission electron microscope (TEM) images show that monodispersed Ag and polydispersed TiO2 nanoparticles have an average diameter of 12 ± 3 nm and 5 ± 1 nm, respectively. Moreover, Fourier transform infrared spectroscopy (FTIR) analysis reveals that Ag nanoparticles were successfully functionalized and capped with... 

    Surface engineering of pbs colloidal quantum dots using atomic passivation for photovoltaic applications

    , Article 8th International Conference on Materials for Advanced Technologies, 28 June 2015 through 3 July 2015 ; Volume 139 , 2016 , Pages 117-122 ; 18777058 (ISSN) Tavakoli, M. M ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    Solution-processed quantum dots (QDs) have attracted significant attention for the low-cost fabrication of optoelectronic devices. Here, we synthesized PbS QDs via hot injection method and passivated the trap states by using short thiols and dopant elements for photovoltaic application. In order to study the effect of dopants on photovoltaic application, PbS QDs were doped by using three different cations: Cadmium, Calcium, and Zinc. We utilized Time resolvel Photoluminescence measurement to study the carriers lifetime for different samples and found that the carriers life time increases ∼80% by using Cd as a dopant compared with undoped sample. In addition, the results of J-V measurement... 

    A facile low temperature route to deposit a TiO2 scattering layer for efficient dye-sensitized solar cells

    , Article RSC Advances ; Volume 6, Issue 75 , 2016 , Pages 70895-70901 ; 20462069 (ISSN) Andaji Garmaroudi, Z ; Abdi Jalebi, M ; Mohammadi, M. R ; Friend, R. H ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Abstract
    Herein, we demonstrate a facile low temperature chemical bath deposition approach to deposit a light scattering layer on a nanostructured mesoporous TiO2 bottom layer in a dye-sensitized solar cell architecture. Large TiO2 nanoparticles were formed on the top surface of photoanode electrodes via hydrolysis of TiCl4 at 70 °C. We controlled the size and agglomeration of these TiO2 nanoparticles by altering the concentration of TiCl4 in the chemical bath during the hydrolysis process. Electron microscope images revealed that mono-dispersed scattering particles having uneven surfaces with diameters between 100 to 300 nm formed on the mesoporous titania layer. The scattering behavior of the... 

    Part load behavior of molten salt cavity receiver solar tower plants under storage mode operational mode

    , Article ASME 2016 10th International Conference on Energy Sustainability, ES 2016, collocated with the ASME 2016 Power Conference and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology, 26 June 2016 through 30 June 2016 ; Volume 1 , 2016 ; 9780791850220 (ISBN) Mostafavi Tehrani, S. S ; Shafiei Ghazani, A ; Taylor, R. A ; Saberi, P ; Sharif University of Technology
    American Society of Mechanical Engineers  2016
    Abstract
    The performance of the tower based concentrated solar thermal (CST-tower) plant is very sensitive to the operation strategy of the plant and the incident heat flux on the receiver. To date, most studies have been examined only the design mode characteristics of the cavity receivers, but this paper significantly expands the literature by considering non-design operating conditions of this important sub-component of the CST-tower plants. A feasible non-design operating conditions of the cavity receivers that was considered in this study is the storage mode of operation. Two practical dynamic control strategies were examined then to find the most efficient approach: fixed solar field mass... 

    Broadband and low-loss plasmonic Light trapping in dye-sensitized solar cells using micrometer-scale rodlike and spherical core-shell plasmonic particles

    , Article ACS Applied Materials and Interfaces ; Volume 8, Issue 25 , 2016 , Pages 16359-16367 ; 19448244 (ISSN) Malekshahi Byranvand, M ; Nemati Kharat, A ; Taghavinia, N ; Dabirian, A ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    Dielectric scattering particles have widely been used as embedded scattering elements in dye-sensitized solar cells (DSCs) to improve the optical absorption of the device. Here we systematically study rodlike and spherical core-shell silica@Ag particles as more effective alternatives to the dielectric scattering particles. The wavelength-scale silica@Ag particles with sufficiently thin Ag shell support hybrid plasmonic-photonic resonance modes that have low parasitic absorption losses and a broadband optical response. Both of these features lead to their successful deployment in light trapping in high-efficiency DSCs. Optimized rodlike silica@Ag@silica particles improve the power conversion... 

    Optimization of photovoltaic electrolyzer hybrid systems; taking into account the effect of climate conditions

    , Article Energy Conversion and Management ; Volume 118 , 2016 , Pages 438-449 ; 01968904 (ISSN) Sayedin, F ; Maroufmashat, A ; Sattari, S ; Elkamel, A ; Fowler, M ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    Solar energy will make a valuable contribution for power generation in the future. However the intermittency of solar energy has become an important issue in the utilization of PV system, especially small scale distributed solar energy conversion systems. The issue can be addressed through the management of production and storage of the energy in the form of hydrogen. The hydrogen can be produced by solar photovoltaic (PV) powered electrolysis of water. The amount of transferred energy to an electrolyzer from a PV module is a function of the distance between maximum power points (MPP) of PV module and the electrolyzer operating points. The distance can be minimized by optimizing the number... 

    Selecting Support Layer for Electrodeposited Efficient Cobalt Oxide/Hydroxide Nanoflakes to Split Water

    , Article ACS Sustainable Chemistry and Engineering ; Volume 4, Issue 6 , 2016 , Pages 3151-3159 ; 21680485 (ISSN) Naseri, N ; Esfandiar, A ; Qorbani, M ; Moshfegh, A. Z ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    Energy and environment crises motivated scientists to develop sustainable, renewable, and clean energy resources mainly based on solar hydrogen. For this purpose, one main challenge is the low cost flexible substrates for designing earth abundant efficient cocatalysts to reduce required water oxidation overpotential. Here, a systematic morphological and electrochemical study has been reported for cobalt oxide/hydroxide nanoflakes simply electrodeposited on four different commercially available substrates, titanium, copper sheet, steel mesh, and nickel foam. Remarkable dependence between the used substrate, morphology, and electrocatalytic properties of nanoflakes introduced flexible porous... 

    Efficient dye-sensitized solar cells based on TiO2 nanoparticles and skein-like nanotubes: effect of arrangement modes of the layers and TiCl4 treatment

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 61 , 2016 , Pages 138-146 ; 18761070 (ISSN) Mojaddami, M ; Andaji Garmaroudi, Z ; Mohammadi, M. R ; Madaah Hosseini, H. R ; Sharif University of Technology
    Abstract
    Herein, we report a double-layer photoanode electrode composed of TiO2 nanoparticles active layer and a mixture of nanoparticles and newly proposed skein-like nanotubes (NTs) top layer. Such structure performs well in solar light harvesting due to first, the top layer exhibits superior light scattering and second, the active layer with high dye-loading can make better use of the back-scattered light. The results reveal that 30-40 nm nanoparticles have anatase structure, whereas 5-7 μm skein-like NTs show a mixture of anatase and rutile phases. Photovoltaic measurements demonstrate that by tuning mass ratio between nanoparticles and skein-like NTs, the cells based on single-layer photoanode... 

    Improving transparency in dye-sensitized nanostructured solar cells by optimizing nano-porous titanium dioxide photo-electrode

    , Article Journal of Materials Science: Materials in Electronics ; Volume 28, Issue 11 , 2017 , Pages 7811-7818 ; 09574522 (ISSN) Nikfarjam, A ; Mohammadpour, R ; Kasaeian, A ; Zebhi, Z ; Sharif University of Technology
    Springer New York LLC  2017
    Abstract
    Today’s the technology based on dye-sensitized solar cells (DSSCs) has an important role in all photovoltaic system technologies. DSSCs can generate electricity with various degrees of transparency; this makes it suitable for use in various industries, especially in construction industry as smart windows. In fact DSSC can produce electricity and having natural light, simultaneously. It is obvious that DSSCs need to absorb solar radiation as much as possible. Since, the effective use of all incident lights leads to an increase in cell efficiency and this increase in efficiency is related to the amount of dye adsorbed on the surface of nanostructured electrode, so higher amount of dye for... 

    Nonlinear adaptive control of grid-connected three-phase inverters for renewable energy applications

    , Article International Journal of Control ; Volume 90, Issue 1 , 2017 , Pages 53-67 ; 00207179 (ISSN) Mahdian Dehkordi, N ; Namvar, M ; Karimi, H ; Piya, P ; Karimi Ghartemani, M ; Sharif University of Technology
    Abstract
    Distributed generation (DG) units are often interfaced to the main grid using power electronic converters including voltage-source converters (VSCs). A VSC offers dc/ac power conversion, high controllability, and fast dynamic response. Because of nonlinearities, uncertainties, and system parameters’ changes involved in the nature of a grid-connected renewable DG system, conventional linear control methods cannot completely and efficiently address all control objectives. In this paper, a nonlinear adaptive control scheme based on adaptive backstepping strategy is presented to control the operation of a grid-connected renewable DG unit. As compared to the popular vector control technique, the... 

    Experimental investigation of a solar still equipped with an external heat storage system using phase change materials and heat pipes

    , Article Desalination ; Volume 409 , 2017 , Pages 128-135 ; 00119164 (ISSN) Faegh, M ; Shafii, M. B ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    In this study, a novel idea of storing the latent heat of condensing vapor in solar stills by means of phase change materials (PCMs) as a thermal storage is experimentally investigated. During the daytime, the generated water vapor by the solar energy, is conducted to an external condenser filled with PCM to be condensed. The wasted latent heat is absorbed by PCM and thereby stored. It is worth noting that there is no direct contact between the saline water and the PCM, therefore, the solar energy is not directly stored in the PCM. In the evening, the energy stored in the PCM is transferred as heat to the saline water by heat pipes and enables the desalination process to continue. Several...