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    Power reduction in HPC data centers: a joint server placement and chassis consolidation approach

    , Article Journal of Supercomputing ; Vol. 70, issue. 2 , 2014 , p. 845-879 Pahlavan, A ; Momtazpour, M ; Goudarzi, M ; Sharif University of Technology
    Abstract
    Size and number of high-performance data centers are rapidly growing all around the world in recent years. The growth in the leakage power consumption of servers along with its exponential dependence on the ever increasing process variation in nanometer technologies has made it inevitable to move toward variation-aware power reduction strategies in data centers. In this paper, we address the problem of joint server placement and chassis consolidation to minimize power consumption of high-performance computing data centers under process variation. To this end, we introduce two variation-aware server placement heuristics as well as an integer linear programming (ILP)-based server placement... 

    Software-level instruction-cache leakage reduction using value-dependence of SRAM leakage in nanometer technologies

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 6590 , 2011 , Pages 275-299 ; 03029743 (ISSN); 9783642194474 (ISBN) Goudarzi, M ; Ishihara, T ; Noori, H ; Stenstrom P ; Sharif University of Technology
    Abstract
    Within-die process variation is increasing in nanometer-scale process technologies. We observe that the same SRAM cell leaks differently under within-die process variations when storing 0 compared to 1; this difference can be up to 3 orders of magnitude at 60mV variation of threshold voltage (V th). Thus, leakage can be reduced if most often the values that dissipate less leakage are stored in the cache SRAM cells. We take advantage of this fact to reduce instruction-cache leakage by presenting three binary-optimization and software-level techniques: we (i) reorder instructions within basic-blocks so that their bits better match the less-leaky state of their corresponding cache cells, (ii)... 

    Simulation of Direct Reduction of Iron Ore Unit In Foolad Mobarakeh Plant And Optimization of Water Consumption

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Mahdieh (Author) ; Farhadi, Fattolah (Supervisor)
    Abstract
    Due to the importance of the direct reduction method in iron and steel production, the optimum operating condition of this unit has an increasing importance. In some areas, because of the climate conditions and geographical situation and inaccessibility to adequate water, supply of required water for the unit is a major problem. So, many attempts have been performed to decrease water consumption in these units. In this thesis, water consumption of the scrubbers in direct reduction unit of Mobarakeh Steel plant is investigated. First, this unit is simulated. Then with solving the set of equations of mass and heat balances of water circulation, the amount of water consumption in these... 

    Pre-reduction of Manganese Ore by Natural Gas for Ferromanganese Production

    , Ph.D. Dissertation Sharif University of Technology Cheraghi, Alireza (Author) ; Yoozbashizadeh, Hossein (Supervisor) ; Safarian, Jafar (Co-Supervisor)
    Abstract
    Pre-reduction of some manganese sources (low-grade Venrach and Godar-Sabz ores, high-grade Comilog ore, pellet, pure oxide) by methane gas has been investigated in this research. HSC-Chemistry and FactSage software were used for thermodynamic study of the process. Thermodynamic results indicated that methane may progress to manganese carbide formation, and the reduction process can run autonomously involving less carbon dioxide emission comparing to common ferromanganese process. Several techniques including XRF, XRD, in-situ XRD, SEM-EDS, and thermogravimetry were used in sample characterization and experiments. In addition to the thermal decomposition reactions which were affected by... 

    Design and Development of an Alternative System of Recycling Exhaust Gas of a Direct Iron Reduction Furnace based on the Criterion of Minimum Destruction of Exergy and Water Usage

    , M.Sc. Thesis Sharif University of Technology Golkar, Babak (Author) ; Sobouhi, Yadollah (Supervisor) ; Ashjari, Mohammad Ali (Co-Advisor)
    Abstract
    Enormous amounts of water and energy are lost by scrubber utilization for furnace exhaust gas washing during direct iron reduction process. Hence, the aim of the current research is design and construction of a system which could be employed instead of scrubber within direct iron reduction process considering the equipment size constraints.To this end, the substitute system was manufactured after dimensional analysis and simulation of lab model compared to the prototype regarding the implementation limitations. The model has been tested in different operating conditions and empirical relations have been extracted for general analysis of direct iron reduction process. The case study here is... 

    Incomplete Reduction of Iron Ore in a Fluidized Bed Reactor

    , M.Sc. Thesis Sharif University of Technology Agha Ali, Mohammad Hadi (Author) ; Halali, Mohammad (Supervisor)
    Abstract
    The main goal of current investigation was partial reduction of Fe2O3 available in Hematite-rich ore to Magnetite by Fludization Bed method. The reductive gas, CO, was produced by incomplete combustion of Acetylene and Airmixed in inappropriate ratio. X-Ray Diffraction and X-Ray Florescence analyses were implemented in order to conducting qualitative analysis of present phases before and after reduction of the ore. Quantitative analysis of the same phases was also conducted by Titration. The latter analysis revealed the precise magnitude of available iron in each of the oxide containing phases. The chemical composition of the reactor gas was also determined before and after reduction... 

    Studying Parameters Affecting the Quality of Sponge Iron Produced by Hoganas Process

    , M.Sc. Thesis Sharif University of Technology Asadi Karam, Amir (Author) ; Halali, Mohammad (Supervisor)
    Abstract
    Hoganas is a gas based process which is more than a hundred years old. In this research, studying parameters affecting the quality of sponge iron like temperature, time, particle size, type of reductant, type and dimension of crucible were discussed. Groups of particle size was 0-150,150-500,500-1000microns and temperature range was 900, 950, 1000, 1100, 1150°C. Time of tests was between 2 to 30 hours.at 1000 °C and 10 hours maximum metallization degree was 94.76.while at 1100 °C and 5hours better metallization degree was achieved. at 1000 °C and 5 h, particles with 500-1000micron size had better result than other groups.at higher temperature effect of particle size was gradually decreased... 

    “Cold Briquetted Iron and Carbon (CBIC)”, Investigation of Oxidation Behavior in Environmental Conditions and Steelmaking Performance

    , Ph.D. Dissertation Sharif University of Technology Paknahad, Pouyan (Author) ; Askari, Masoud (Supervisor)
    Abstract
    Cold Briquetted Iron and Carbon (CBIC) is a new product in Direct Reduced Iron (DRI) family that aims to produce a reliable product from Cold Direct Reduced Iron (CDRI) with the ability of low risk, high efficient storage and handling. In this study, a comprehensive investigation was carried out on the effects of environmental condition on physical and chemical properties of CBIC, CDRI and Hot Briquetted Iron (HBI) in the first step and then, the steelmaking performance of this new product was compared to the other DRI products in the second step. The changes of microstructure, specific surface area, metallization degree and mechanical strength of different products with time in dry and... 

    Increasing Carbon Percentage of Hoganas Sponge Iron

    , M.Sc. Thesis Sharif University of Technology Niknahad, Niusha (Author) ; Halali, Mohammad (Supervisor)
    Abstract
    The sponge iron of the Hoganas process have a high metallization degree (93-96%) and its carbon content is about 0.1%. These characteristics are suitable for powder metallurgy but in order to use this DRI for steelmaking, it needs lower metallization degree and higher content of carbon. First, for using Hoganas sponge iron for steel production, 94% of metallization is adequate as some of iron is still in the form of FeO which its reduction in Electric Arc Furnace (EAF) cause better agitation in order to utilize heat transfer. Also, excess carbon content in the DRI can have many advantages other than preventing the sponge iron from re-oxidation. Some of the carbon can be in the form of Fe3C... 

    Variation-aware server placement and task assignment for data center power minimization

    , Article Proceedings of the 2012 10th IEEE International Symposium on Parallel and Distributed Processing with Applications, ISPA 2012 ; 2012 , Pages 158-165 ; 9780769547015 (ISBN) Pahlavan, A ; Momtazpour, M ; Goudarzi, M ; Sharif University of Technology
    2012
    Abstract
    Size and number of data centers are fast growing all over the world and their increasing total power consumption is a worldwide concern. Moreover, increase in the amount of process variation in nanometer technologies and its effect on total power consumption of servers has made it inevitable to move toward variation-aware power reduction strategies. This paper formulates a variation-aware joint server placement and task assignment method using Integer Linear Programming (ILP) to minimize total power consumption of data centers. We first determine the optimum placement of servers in the data center racks based on total power consumption of each server and the data center recirculation model... 

    Skewness reduction approach in multi-attribute process monitoring

    , Article Communications in Statistics - Theory and Methods ; Volume 36, Issue 12 , 2007 , Pages 2313-2325 ; 03610926 (ISSN) Akhavan Niaki , S. T ; Abbasi, B ; Sharif University of Technology
    2007
    Abstract
    Since the product quality of many industrial processes depends upon more than one dependent variable or attribute, they are either multivariate or multi-attribute in nature. Although multivariate statistical process control is receiving increased attention in the literature, little work has been done to deal with multi-attribute processes. In this article, we develop a new methodology to monitor multi-attribute processes. To do this, first we transform multi-attribute data in a way that their marginal probability distributions have almost zero skewness. Then, we estimate the transformed covariance matrix and apply the well-known T2 control chart. In order to illustrate the proposed method... 

    Reactivity and characteristics of Pd/MOF and Pd/calcinated-MOF catalysts for CO oxidation reaction: Effect of oxygen and hydrogen

    , Article International Journal of Hydrogen Energy ; Volume 46, Issue 24 , 2021 , Pages 12822-12834 ; 03603199 (ISSN) Abbasi, F ; Karimi Sabet, J ; Ghotbi, C ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    For the first time, the effect of calcination process on characteristics and catalytic performances of Pd supported on different MOFs (MIL-101(Cr), NH2-MIL-101(Cr), and HKUST-1) was evaluated. Besides, the various orders of calcination process and reduction one on Pd/MOF and Pd/calcinated-MOF were studied, and their performances in CO oxidation reaction were presented to find the effect of H2 and O2. Results showed that the effect of calcination and reduction processes on the catalytic activities and characteristics strongly depends on the nature of MOF. Among MIL-based catalysts, the catalyst with no calcination treatment showed the best activity. Among MNH2-based catalysts, high activity... 

    Reactivity and characteristics of Pd/MOF and Pd/calcinated-MOF catalysts for CO oxidation reaction: Effect of oxygen and hydrogen

    , Article International Journal of Hydrogen Energy ; Volume 46, Issue 24 , 2021 , Pages 12822-12834 ; 03603199 (ISSN) Abbasi, F ; Karimi Sabet, J ; Ghotbi, C ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    For the first time, the effect of calcination process on characteristics and catalytic performances of Pd supported on different MOFs (MIL-101(Cr), NH2-MIL-101(Cr), and HKUST-1) was evaluated. Besides, the various orders of calcination process and reduction one on Pd/MOF and Pd/calcinated-MOF were studied, and their performances in CO oxidation reaction were presented to find the effect of H2 and O2. Results showed that the effect of calcination and reduction processes on the catalytic activities and characteristics strongly depends on the nature of MOF. Among MIL-based catalysts, the catalyst with no calcination treatment showed the best activity. Among MNH2-based catalysts, high activity... 

    Numerical Modeling of Reformer in Direct Reduction Plants

    , M.Sc. Thesis Sharif University of Technology Karami, Mitra (Author) ; Afshin, Hossein (Supervisor) ; Farhanieh, Bijan (Supervisor)
    Abstract
    Direct reduction of iron is a process to reduce iron in solid phase. The output of this procedure is direct reduced iron (DRI) that can be used in electric arc furnacewithout further changes. Midrex technology, which is the most important one among direct reduction of iron processes, provides 60% of DRI.
    Required synthesis gas for reduction process is gained from reforming of the natural gas,with the major proportion of methane, with water steam and carbon dioxide in a piece of equipment called “reformer”. As a matter of fact, reformer is a type of plug chemical reactors. Input materials (natural gas, water steam and carbon dioxide) enter from the bottom section to the prepared pipes in... 

    Study the Effect of Carbon Content Exist in Midrex Cold Briquetted Sponge Iron on Melting Performance and Comparison with DRI and HBI

    , M.Sc. Thesis Sharif University of Technology Ranjbar, Hassan (Author) ; Askari, Masoud (Supervisor)
    Abstract
    Midrex sponge iron is an active product and there are several problems with store and export it.Cold briquetting sponge iron method is a new method to protect sponge iron from oxidation and provides the possibility of its storage and transportation. Iran as one of the biggest countries that produce sponge iron, has a lot of sponge iron pilots that equipped with cold briquetted machines,but their production capacity is limited and is about 5 percent of their production capacity. With regard to no need for country to these amount of sponge iron, most of these pilots have to store and transport large volumes of sponge iron and the risk of oxidation and fire threatens these units.By using cold... 

    Simulation of Direct Reduction Shaft Furnace Based on Inverse Method

    , M.Sc. Thesis Sharif University of Technology Beikzadeh, Pouria (Author) ; Saboohi, Yadollah (Supervisor)
    Abstract
    DIRECT reduction is a process for reducing iron ore in the solid state. The product is in the form of sponge iron. This can be used directly as a raw material for steelmaking in an electric arc furnace. MIDREX process produces more than 60 percent of global DRI production. Because of high potential natural gas and iron ore resources in Iran and also lack of scarp, MIDREX direct reduction process is feasible. The main function of the MIDREX shaft furnace is to generate sponge iron from iron ore. The solids flow downwards by gravity and the reducing gases flow upwards in counter current, while the corresponding chemical transformations occur. Physical phenomena in the reactor could be... 

    Improving the multi-step fabrication approach of copper nanofiber networks based transparent electrode for achieving superb conductivity and transparency

    , Article Materials Research Express ; Volume 6, Issue 9 , 2019 ; 20531591 (ISSN) Mohamadbeigi, N ; Angizi, S ; Sadrnezhaad, S. K ; Nikzad, M. J ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Abstract
    Transparent Conductive Electrode (TCE), as an essential part of the optoelectronic devices, has become popular owing to its unique properties such as high optical transmittance and conductivity. Among utilized materials for fabrication of TCE, copper nanofibers (NFs)-network have been attracting much attention due to its extraordinary properties such as low sheet resistance, the scalable manufacturing and low-cost fabrication method. However, many challenges exist in the way of multi-step fabrication of network to increase the NFs continuity and consequently, improvement of their electrical conductivity as TCE. Herein, we report a deep investigation of the effective parameters on diameter... 

    Solid state reduction of Iranian titanomagnetite concentrate optimization and study

    , Article Mineral Processing and Extractive Metallurgy: Transactions of the Institute of Mining and Metallurgy ; 2019 ; 25726641 (ISSN) Poyanfar, S ; Askari, M ; Sharif University of Technology
    Taylor and Francis Ltd  2019
    Abstract
    An attempt was made to produce an iron bearing and a titanium bearing product, using solid state reduction of Fanouj mine titanomagnetite concentrate. For this purpose, the concentrate was mixed with pulverised coal and sodium carbonate and was reduced in a muffle furnace. The product was then subjected to magnetic separation. In this work, the effect of temperature, time, added coal and additive amount on reduction was studied. The Separation Efficiency (SE) index was used for optimisation of the process. Using SE is more appropriate than degree of metallization, which is usually used, for optimising reduction processes. The results show that the optimal conditions are 1325°C, 2.5 h, 25... 

    Improving the multi-step fabrication approach of copper nanofiber networks based transparent electrode for achieving superb conductivity and transparency

    , Article Materials Research Express ; Volume 6, Issue 9 , 2019 ; 20531591 (ISSN) Mohamadbeigi, N ; Angizi, S ; Sadrnezhaad, S. K ; Nikzad, M. J ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Abstract
    Transparent Conductive Electrode (TCE), as an essential part of the optoelectronic devices, has become popular owing to its unique properties such as high optical transmittance and conductivity. Among utilized materials for fabrication of TCE, copper nanofibers (NFs)-network have been attracting much attention due to its extraordinary properties such as low sheet resistance, the scalable manufacturing and low-cost fabrication method. However, many challenges exist in the way of multi-step fabrication of network to increase the NFs continuity and consequently, improvement of their electrical conductivity as TCE. Herein, we report a deep investigation of the effective parameters on diameter... 

    Efficient CO oxidation over palladium supported on various MOFs: Synthesis, amorphization, and space velocity of hydrogen stream

    , Article International Journal of Hydrogen Energy ; Volume 45, Issue 41 , 2020 , Pages 21450-21463 Abbasi, F ; Karimi Sabet, J ; Ghotbi, C ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Amine-functionalized MIL-101(Cr) has been synthesized by hydrothermal (MNH2) and post-synthetic modification (MNH2-p) approaches. Pd/MNH2 and Pd/MNH2-p have been tested in CO oxidation reaction as a gas phase reaction to clarify the difference between two synthesis approaches. Their performance has also been compared with that of Pd supported on MIL as a common MOF and CuBTC as a commercial one. The results show the significant difference between Pd/MNH2-p and Pd/MNH2, where CO conversion of 100% was not observed for Pd/MNH2-p, whereas Pd/MNH2 outperformed the others and exhibited the high reaction rate thanks to the active sites created by amorphization during the reduction process because...