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    A system dynamics approach to the seismic resilience enhancement of hospitals

    , Article International Journal of Disaster Risk Reduction ; Volume 31 , 2018 , Pages 220-233 ; 22124209 (ISSN) Khanmohammadi, S ; Farahmand, H ; Kashani, H ; Sharif University of Technology
    Elsevier Ltd  2018
    In the aftermath of earthquakes, hospitals serve the critical role of treating casualties. In many cases, the key components of a hospital (i.e., the building, staff, medicine inventory, technical systems, and medical equipment) are affected by an earthquake. To handle the demand surge, affected hospitals should recover in an effective manner. Hospital recovery is a complex and dynamic process because each component requires specific types and amount of resources to recover. Furthermore, the recovery of each component not only affects its performance but also plays a role in the overall hospital recovery. Hospital administrators need to model the complex recovery process after a future... 

    Dislocation network formation during creep in Ni-base superalloy GTD-111

    , Article Materials Science and Engineering A ; Volume 339, Issue 1-2 , 2003 , Pages 103-108 ; 09215093 (ISSN) Nategh, S ; Sajjadi, S. A ; Sharif University of Technology
    The Ni-base superalloy GTD-111 is used as a blading material in the first stage blades of high power gas turbines. The creep-rupture properties of the cast superalloy were studied over a wide range of temperatures and stresses. The observations of dislocation structures during steady-state creep confirmed that the creep mechanism was different in the high and low stress regions. The results showed that in the high stress region, shear mechanisms including stacking fault formation and anti-phase boundary creation were operative and in the low stress region, a by-passing mechanism occurred by either looping or dislocation climb and glide. With increasing exposure time in the high-temperature... 

    UCS-NT: An unbiased compressive sensing framework for Network Tomography

    , Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; 2013 , Pages 4534-4538 ; 15206149 (ISSN) ; 9781479903566 (ISBN) Mahyar, H ; Rabiee, H. R ; Hashemifar, Z. S ; Sharif University of Technology
    This paper addresses the problem of recovering sparse link vectors with network topological constraints that is motivated by network inference and tomography applications. We propose a novel framework called UCS-NT in the context of compressive sensing for sparse recovery in networks. In order to efficiently recover sparse specification of link vectors, we construct a feasible measurement matrix using this framework through connected paths. It is theoretically shown that, only O(k log(n)) path measurements are sufficient for uniquely recovering any k-sparse link vector. Moreover, extensive simulations demonstrate that this framework would converge to an accurate solution for a wide class of... 

    Application of the recovery curve method for evaluation of matrix-fracture interactions

    , Article Journal of Natural Gas Science and Engineering ; Volume 22 , January , 2015 , Pages 447-458 ; 18755100 (ISSN) Ghaedi, M ; Masihi, M ; Heinemann, Z. E ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier  2015
    The Discrete Fracture Network and Dual Continuum concept are two common methods to model naturally fractured reservoirs. Each has specific limitations. The newly introduced recovery curve method is believed to be a compromise between these two current methods. In the recovery curve method, two recovery curves for water and gas displacements are used to more realistically calculate matrix-fracture mass exchanges. This paper presents a new approach to determine appropriate recovery curves by using the recovery curve method and production data. In particular, two recovery curves were determined for a column model by matching phase contact positions throughout the production data. Hybrid genetic... 

    Modeling and optimizing recovery strategies for power distribution system resilience

    , Article IEEE Systems Journal ; Volume 15, Issue 4 , 2021 , Pages 4725-4734 ; 19328184 (ISSN) Arjomandi Nezhad, A ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Safdarian, A ; Dehghanian, P ; Wang, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Both frequency and intensity of natural disasters have intensified in recent years. It is, therefore, essential to design effective strategies to minimize their catastrophic consequences. Optimizing recovery tasks, including distribution system reconfiguration (DSR) and repair sequence optimization (RSO), are the key to enhance the agility of disaster recovery. This article aims to develop a resilience-oriented DSR and RSO optimization model and a mechanism to quantify the recovery agility. In doing so, a new metric is developed to quantify the recovery agility and to identify the optimal resilience enhancement strategies. The metric is defined as 'the number of recovered customers divided... 

    Exergy Analysis on Design of SMR Preheating Exchangers

    , M.Sc. Thesis Sharif University of Technology Shariati, Mohammad Hassan (Author) ; Farhadi, Fathollah (Supervisor)
    With the global oil price increase in recent years and fossil fuel resource scarcity, analyzing of fossil fuel consumer industries and optimization of their fuel consumption is an important rule. Exergy analysis is an efficient tool for this purpose in the chemical and petrochemical processes in recent years more than ever. Therefore, in this work, an exergy analysis is performed for heat recovery section of Steam-Methane Reforming (SMR) process as a major consumer of natural gas.
    This work contains five general section. At the first section, exergy and energy concepts, reforming processes and other related basic concepts are described. The second section is about the recent research and... 

    The impact of silica nanoparticles on the performance of polymer solution in presence of salts in polymer flooding for heavy oil recovery

    , Article Fuel ; Vol. 123 , May , 2014 , pp. 123-132 ; ISSN: 00162361 Maghzi, A ; Kharrat, R ; Mohebbi, A ; Ghazanfari, M. H ; Sharif University of Technology
    Due to role of polymer in increasing sweep efficiency during oil recovery, much attention has been paid to the using polymer solutions in enhanced oil recovery methods. In spite of the existence of the great researches in this area, the role of nanoparticles in modification of the polymer performance in the presence of salts has not been examined before. Furthermore, there is no information about how the dispersed silica nanoparticles affect the heavy oil recovery during the polymer flooding in the presence of divalent cations. In this study, a series of polymer flooding experiments are performed in a quarter five-spot glass micromodel saturated with heavy oil. Solutions of polyacrylamide... 

    The simulation of microbial enhanced oil recovery by using a two-layer perceptron neural network

    , Article Petroleum Science and Technology ; Vol. 32, Issue. 22 , 2014 , pp. 2700-2707 ; ISSN: 10916466 Morshedi, S ; Torkaman, M ; Sedaghat, M. H ; Ghazanfari M.H ; Sharif University of Technology
    The authors simulated a reservoir by using two-layer perceptron. Indeed a model was developed to simulate the increase in oil recovery caused by bacteria injection into an oil reservoir. This model was affected by reservoir temperature and amount of water injected into the reservoir for enhancing oil recovery. Comparing experimental and simulation results and also the erratic trend of data show that the neural networks have modeled this system properly. Considering the effects of nonlinear factors and their erratic and unknown impacts on recovered oil, the perceptron neural network can develop a proper model for oil recovery factor in various conditions. The neural networks have not been... 

    Corrigendum to "ISI sparse channel estimation based on SL0 and its application in ML sequence-by-sequence equalization" [Signal Processing 92 (2012) 1875-1885] (DOI:10.1016/j.sigpro.2011.09.035)

    , Article Signal Processing ; 2013 ; 01651684 (ISSN) Niazadeh, R ; Hamidi Ghalehjegh, S ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
    In this paper, which is an extended version of our work at LVA/ICA 2010 [1], the problem of Inter Symbol Interface (ISI) Sparse channel estimation and equalization will be investigated. We firstly propose an adaptive method based on the idea of Least Mean Square (LMS) algorithm and the concept of smoothed l0 (SL0) norm presented in [2] for estimation of sparse ISI channels. Afterwards, a new non-adaptive fast channel estimation method based on SL0 sparse signal representation is proposed. ISI channel estimation will have a direct effect on the performance of the ISI equalizer at the receiver. So, in this paper we investigate this effect in the case of optimal Maximum Likelihood... 

    Experimental analysis of secondary gas injection strategies

    , Article Petroleum Science and Technology ; Volume 31, Issue 8 , 2013 , Pages 797-802 ; 10916466 (ISSN) Heidari, P ; Alizadeh, N ; Kharrat, R ; Ghazanfari, M. H ; Laki, A. S ; Sharif University of Technology
    CO2 injection is a potentially viable method of enhanced oil recovery for medium oil reservoirs. The authors compare the effect of gas injection strategy (simultaneous water-alternating gas [SWAG], water-alternating gas [WAG], and continuous gas injection [CGI]) on recovery in immiscible, near-miscible, and miscible modes of injection. It has been proved that CGI is not the most efficient injection scenario in oil-wet reservoirs. Miscible and near-miscible core flood tests demonstrated high oil recoveries in all injection strategies due to high capillary numbers achieved as a result of miscibility. The fluid mechanics of floods were discussed using pressure drop data, different mechanics was... 

    Cover picture: Nanostructured particles for controlled polymer release in enhanced oil recovery (energy technol. 9/2016)

    , Article Energy Technology ; Volume 4, Issue 9 , 2016 , Pages 1029- ; 21944288 (ISSN) Tamsilian, Y ; Ramazani S., A ; Shaban, M ; Ayatollahi, S ; de la Cal, J. C ; Sheng, J. J ; Tomovska, R ; Sharif University of Technology
    Wiley-VCH Verlag  2016
    Abstract original image Smart Enhanced Oil Recovery Process using Core–Shell Nanoparticles: The cover image denotes schematically the enhanced oil recovery process by flooding using an aqueous dispersion of core–shell nanoparticles made up of protected polyacrylamide nanostructures (PPNs). Y. Tamsilian and his colleagues at Sharif University of Technology (Iran) and the Institute for Polymer Material (POLYMAT, Spain) demonstrated the synthesis of polyacrylamide nanoparticles protected with a hydrophobic polystyrene shell by using a one-pot, two-step inverse emulsion polymerization technique, where the polystyrene shell was created by surface polymerization. The presence of the hydrophobic... 

    Upper bounds on the error of sparse vector and low-rank matrix recovery

    , Article Signal Processing ; Volume 120 , 2016 , Pages 249-254 ; 01651684 (ISSN) Malek Mohammadi, M ; Rojas, C.R ; Jansson, M ; Babaie Zadeh, M ; Sharif University of Technology
    Elsevier  2016
    Suppose that a solution x to an underdetermined linear system b=Ax is given. x is approximately sparse meaning that it has a few large components compared to other small entries. However, the total number of nonzero components of x is large enough to violate any condition for the uniqueness of the sparsest solution. On the other hand, if only the dominant components are considered, then it will satisfy the uniqueness conditions. One intuitively expects that x should not be far from the true sparse solution x0. It was already shown that this intuition is the case by providing upper bounds on ||x-x0|| which are functions of the magnitudes of small components of x but independent from x0. In... 

    Recovery of surfactants from oil in water emulsions by electroflotation

    , Article 8th World Congress of Chemical Engineering: Incorporating the 59th Canadian Chemical Engineering Conference and the 24th Interamerican Congress of Chemical Engineering, 23 August 2009 through 27 August 2009, Montreal, QC ; 2009 Biria, D ; Mansouri, M ; Maghsoudi, E ; Roostaazad, R ; Dadafarin, H ; Sharif University of Technology
    An electroflotation technique was utilized to reclaim the surfactant molecules from oil-in-water emulsions. A two-staged separation mechanism was suggested to describe the process. The surfactant recovery efficiencies were higher than 70% after 30 min treatment. The method could be an effective process in recycling surfactants from the emulsions existing in industrial wastes. This is an abstract of a paper presented at the 8th World Congress of Chemical Engineering (Montreal, Quebec, Canada 8/23-27/2009)  

    Separation and recovery of cobalt catalyst from wastewater of PTA unit

    , Article Reviews in Inorganic Chemistry ; Volume 29, Issue 3 , 2009 , Pages 171-179 ; 01934929 (ISSN) Sajadi, S. A. A ; Abdolahifar, A ; Jafarbegloo, M ; Sharif University of Technology
    The goal of this work is separation and recovery of catalyst residue in wastewater and byproducts of PTA (poly terephetalic acid) unit. Catalyst recovery consists in separating the maximum amount of catalyst and changing the same into valuable compounds. The PTA unit uses cobalt catalyst for oxidation reactions. The byproducts, which contain catalyst, were burned. In the case of metal oxide recovery in the ashes of waste materials, we could solve the problem of the Petrochemical Company. This new method may help us to recover catalyst from wastewater in PTA unit, after which small amounts of ions may be absorbed on a column filled with special absorbent, in such a way that the wastewater... 

    Effect of magnetic field treatment on interfacial tension of CTAB nano-emulsion: developing a novel agent for enhanced oil recovery

    , Article Journal of Molecular Liquids ; Volume 261 , July , 2018 , Pages 107-114 ; 01677322 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2018
    Nanoemulsion is a novel type of emulsified solutions holding great promises for utilizing in industrial applications. Although microemulsions have been the subject of numerous studies in past decades, however, nanoemulsions are quite virgin and merit detailed investigation to scrutinize their characteristics specific to reservoir engineering, in particular, Enhanced Oil Recovery (EOR). To this end, the present study is an attempt to evaluate the effectiveness of a specific nanoemulsion for oil displacement through porous media. In this regard, flooding experiments were designed and Hexa decyl trimethylammonium bromide (CTAB), which is a cationic surfactant, was used as the emulsifying agent.... 

    A proposed design method for supersonic inlet to improve performance parameters

    , Article Aerospace Science and Technology ; Volume 91 , 2019 , Pages 583-592 ; 12709638 (ISSN) Farahani, M ; Mahdavi, M. M ; Sharif University of Technology
    Elsevier Masson SAS  2019
    A new structure for the compression surfaces of a supersonic inlet is proposed which has improved the target performance parameter i.e. total pressure recovery ratio. This idea resulted in development of a new type of supersonic inlet, utilized four ramps and a cone simultaneously as the compression surfaces. A prototype of the proposed inlet has been designed for a free stream Mach number of 3 and its performance has been evaluated via numerical simulation for both design and off-design conditions. The performance of the newly designed inlet has been compared to the existing experimental data of two double-cone inlets. The acquired data are further compared with analytical calculations of... 

    A survey on exergy, energy and environmental analysis of sulfur recovery unit in case of five intensified configurations

    , Article Chemical Papers ; Volume 73, Issue 6 , 2019 , Pages 1529-1539 ; 03666352 (ISSN) Rostami, A ; Tavan, Y ; Sharif University of Technology
    Springer International Publishing  2019
    In this study, a combination of energy and exergy analysis is applied for the industrial sulfur recovery unit (SRU) in commercial simulation software. The data of energy and exergy are obtained from the simulator and Excel (for physical and chemical exergy), respectively. In doing so, five intensified SRU configurations namely: (1) hot gas bypass (2) acid gas bypass (3) inlet stream preheating (4) acid gas enrichment and (5) oxygen (air) enrichment are compared in terms of energy production, reaction furnace temperature, sulfur recovery and pollutant emission into environment. Then, irreversibility in these five arrangements is compared and all the proposed methods show higher useful exergy... 

    Random sampling with iterative recovery for Millimeter-Wave imaging systems

    , Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 67, Issue 12 , 2020 , Pages 3522-3526 Zamani, H ; Fakharzadeh, M ; Amini, A ; Marvasti, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    In this brief, an imaging methodology for mono-static millimeter-wave systems is introduced. When the measured object hologram is piece-wise smooth with sharp boundaries, both low-pass and high-pass components are present in a transform domain. Nevertheless, the edges are sparse in transform domain with respect to the image dimensions. It is shown that the down-sampling of the hologram with an appropriate rate determined by the sparsity level, includes the adequate information of all components for image reconstruction. Using random samples, an algorithm is proposed to recover all the sparse components, iteratively. Simulation results illustrate that a high-resolution recovery can be... 

    Exergy analysis and optimization of natural gas liquids recovery unit

    , Article International Journal of Air-Conditioning and Refrigeration ; Volume 29, Issue 1 , 2021 ; 20101325 (ISSN) Khajehpour, H ; Norouzi, N ; Shiva, N ; Mahmoodi Folourdi, R ; Hashemi Bahremani, E ; Sharif University of Technology
    World Scientific  2021
    The Natural Gas Liquids (NGL) recovery unit is one of the processes that requires cooling. The sweetened gas enters this unit after the dehydration stage, and the final product called NGL Product is stored and ready for consumption or export. In this research, the first, one of the NGL units, is simulated with HYSYS software. Three types of processes with different cooling systems are studied using the exergy analysis method. Joule-Thomson's combination with the expander is selected for its high exergy efficiency, and the exergy efficiency function has been selected as the objective function 1 to optimize this process mathematically based on this study's findings. The critical term in this... 

    Prediction of flow behavior during warm working

    , Article ISIJ International ; Volume 44, Issue 11 , 2004 , Pages 1867-1873 ; 09151559 (ISSN) Serajzadeh, S ; Sharif University of Technology
    Iron and Steel Institute of Japan  2004
    In this work, the effects of dynamic strain aging and dynamic recovery on metal flow during warm working are studied. Compression experiments are utilized to assess the flow behavior of a low carbon steel under warm deformation conditions. Then, a two dimensional finite element routine is coupled with dynamic recovery and dynamic strain aging models. In this way, the temperature and the velocity fields are predicted during warm working operations with regard to the effects of dynamic recovery and dynamic strain aging. Warm rolling tests are performed in order to verify the modelling results. Comparison between the predicted and measured roll forces shows reliability of the employed model