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Prediction of flow behavior during warm working
, Article ISIJ International ; Volume 44, Issue 11 , 2004 , Pages 1867-1873 ; 09151559 (ISSN) ; Sharif University of Technology
Iron and Steel Institute of Japan
2004
Abstract
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
Prediction of flow stress at hot working condition
, Article Mechanics Research Communications ; Volume 30, Issue 1 , 2003 , Pages 87-93 ; 00936413 (ISSN) ; Taheri, A. K ; Sharif University of Technology
2003
Abstract
A mathematical model has been developed to determine flow stress at hot deformation condition. The proposed model is capable of including work softening due to dynamic phase transformations as well as the effect of temperature and strain rate variation on flow stress utilizing the additivity rule for strain. To verify the model, hot compression tests for two grades of steels has been carried out. The comparison between the experimental and theoretical results confirms the validity of the model
Isolation of penicillin G acylase from Escherichia coli ATCC 11105 by physical and chemical treatments
, Article Biochemical Engineering Journal ; Volume 8, Issue 3 , 2001 , Pages 223-227 ; 1369703X (ISSN) ; Ardjmand, M ; Fazelinia, H ; Zakeri, A ; Sharif University of Technology
2001
Abstract
Different techniques including toluene-ethanol, guanidine hydrochloride, guanidine hydrochloride-EDTA, lysozyme, lysozyme-EDTA and sonication treatments were used to extract penicillin G acylase from Escherichia coli ATCC 11105 cells. The obtained results show that penicillin G acylase extraction by guanidine-EDTA treatment is more specific in comparison to the other applied methods. The maximum specific activity of the enzyme (5.61 U/mg), i.e. the maximum purification was found when 1 M guanidine + 100 mM EDTA solution was used for penicillin G acylase extraction at culture condition including 0.50% (w/v) yeast extract as carbon source. In such a condition more than 95% of the enzyme was...
Investigating the fracture network effects on sweep efficiency during wag injection process
, Article Transport in Porous Media ; Volume 93, Issue 3 , July , 2012 , Pages 577-595 ; 01693913 (ISSN) ; Ghorbanizadeh, S ; Ayatollahi, S ; Sharif University of Technology
2012
Abstract
In this study, the main recovery mechanisms behind oil/water/gas interactions during the water-alternating-gas (WAG) injection process, in a network of matrix/fracture, were fundamentally investigated. A visual micromodel was utilized to provide insights into the potential applications of WAG process in fractured oil-wet media as well as the possibility of observing microscopic displacement behavior of fluids in the model. The model was made of an oil-wet facture/matrix network system, comprised of four matrix blocks surrounded with fractures. Different WAG injection scenarios, such as slug arrangements and the effects of fluid injection rates on oil recovery were studied. A new equation...
A certificate-based proxy signature with message recovery without bilinear pairing
, Article Security and Communication Networks ; Volume 9, Issue 18 , 2016 , Pages 4983-4991 ; 19390114 (ISSN) ; Mohajery, J ; Salmasizadeh, M ; Sharif University of Technology
John Wiley and Sons Inc
2016
Abstract
In this paper, we propose the first provable secure certificate-based proxy signature (CBPS) with message recovery without bilinear pairing. In 2003, Gentry introduced the concept of certificate-based cryptography to solve certificate management and key escrow problems in public key infrastructure and identity-based cryptosystems, respectively. Because the overall cost of pairing computation is higher than scalar multiplication (e.g., over elliptic curve group), consequently, the CBPS schemes without pairings would be more efficient. According to the available research in this regard, our scheme is the first provable secure CBPS scheme with message recovery that is based on the elliptic...
CodedSketch: A coding scheme for distributed computation of approximated matrix multiplication
, Article IEEE Transactions on Information Theory ; Volume 67, Issue 6 , 2021 , Pages 4185-4196 ; 00189448 (ISSN) ; Maddah Ali, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this paper, we propose CodedSketch, as a distributed straggler-resistant scheme to compute an approximation of the multiplication of two massive matrices. The objective is to reduce the recovery threshold, defined as the total number of worker nodes that the master node needs to wait for to be able to recover the final result. To exploit the fact that only an approximated result is required, in reducing the recovery threshold, some sorts of pre-compression are required. However, compression inherently involves some randomness that would lose the structure of the matrices. On the other hand, considering the structure of the matrices is crucial to reduce the recovery threshold. In...
Investigation of oil recovery and CO2 storage during secondary and tertiary injection of carbonated water in an Iranian carbonate oil reservoir
, Article Journal of Petroleum Science and Engineering ; Volume 137 , 2016 , Pages 134-143 ; 09204105 (ISSN) ; Ayatollahi, S ; Riazi, M ; Sharif University of Technology
Elsevier
Abstract
Gas injection process for more oil recovery and in particular CO2 injection is well-established method to increment oil recovery from underground oil reservoirs. CO2 sequestration which takes place during this enhanced oil recovery (EOR) method has positive impact on reducing the greenhouse gas emission which causes global warming. Direct gas injection into depleted oil reservoirs, encounters several shortcomings such as low volumetric sweep efficiency, early breakthrough (BT) and high risk of gas leakage in naturally fractured carbonate oil reservoirs. Carbonated water injection (CWI) has been recently proposed as an alternative method to alleviate the problems associated with gas...
Coupled optimization of enhanced gas recovery and carbon dioxide sequestration in natural gas reservoirs: Case study in a real gas field in the south of Iran
, Article International Journal of Greenhouse Gas Control ; Volume 17 , 2013 , Pages 515-522 ; 17505836 (ISSN) ; Jamshidi, S ; Soltanieh, M ; Sharif University of Technology
2013
Abstract
Since the beginning of industrial age the atmospheric concentration of greenhouse gases has been increased significantly due to excessive use of fossil fuels. An effective way for decreasing emission of greenhouse gases is injection of CO2 in geological formations. Moreover, from the reservoir engineering point of view, CO2 injection has been considered as a method of enhancing oil and gas recovery. While using CO2 for enhanced oil recovery (EOR) has been the subject of several studies in the past decades, enhanced gas recovery (EGR) has not been fully studied in the gas reservoirs, mainly because of high recovery factor of gas reservoirs and mixing of the reservoir gas and CO2. In this...
An experimental investigation of the effect of fracture dip angle on oil recovery and drainage rate in free fall gravity drainage in fractured reservoirs using a glass micromodel (A pore level investigation)
, Article Petroleum Science and Technology ; Volume 31, Issue 4 , 2013 , Pages 355-367 ; 10916466 (ISSN) ; Kharrat, R ; Ghazanfari, M ; Sharif University of Technology
2013
Abstract
Gravity drainage is the main production mechanism in the gas invaded zone in naturally fractured reservoirs. However, there are large ambiguities and complexities, resulting from the dynamic of oil depletion from matrix blocks toward the fracture network. Visualization of drained oil at pore scale using glass micromodels provides the opportunity to better understand the effects of different parameters which might affect oil recovery from fractured reservoirs. In this work a micromodel apparatus generated by laser etching is used to perform some gravity drainage tests on the network patterns. The experiments were performed on double block systems using crude oil. The block to block...
A technical feasibility analysis to apply Pseudomonas aeroginosa MR01 biosurfactant in microbial enhanced oil recovery of low-permeability carbonate reservoirs of Iran
, Article Scientia Iranica ; Volume 17, Issue 1 C , JANUARY-JUNE , 2010 , Pages 46-54 ; 10263098 (ISSN) ; Roostaazad, R ; Kamali, M. R ; Bagheri Lotfabad, T ; Sharif University of Technology
2010
Abstract
The effect of an efficient biosurfactant produced from Pseudomonas aeroginosa MR01, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks, was investigated. In a core holder set-up, bearing a number of limestone-and dolomite-containing core samples, biosurfactant flooding resulted in oil recoveries as large as 20% to 28% Residual Oil (R.O). Biosurfactant injection in less permeable rocks in a range of 0.5 to 32 md was more successful, in terms of oil production. In the case of the least oil recovery via biosurfactant flooding, incubation of the core with a biosurfactant solution at reservoir conditions,...
Experimental study of solvent flooding to heavy oil in fractured five-spot micro-models: The role of fracture geometrical characteristics
, Article Journal of Canadian Petroleum Technology ; Volume 49, Issue 3 , 2010 , Pages 36-43 ; 00219487 (ISSN) ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
2010
Abstract
The solvent-based process appears to be an increasingly feasible technology for the extraction of heavy oil reserves. However, there is a lack of fundamental understanding of how fracture geometrical characteristics control the oil recovery efficiency in this type of enhanced oil recovery (EOR) technique. In this work, a series of experiments were performed whereby the pure and mixed hydrocarbon solvents (HCS) displaced heavy oil in fractured five-spot glass micro-models. Successive images of the solvent injection process were recorded. The oil recovery factor, as a function of injected pore volume of solvents, was measured using image analysis of the provided pictures. It has been observed...
A low-cost sparse recovery framework for weighted networks under compressive sensing
, Article Proceedings - 2015 IEEE International Conference on Smart City, SmartCity 2015, Held Jointly with 8th IEEE International Conference on Social Computing and Networking, SocialCom 2015, 5th IEEE International Conference on Sustainable Computing and Communications, SustainCom 2015, 2015 International Conference on Big Data Intelligence and Computing, DataCom 2015, 5th International Symposium on Cloud and Service Computing, SC2 2015, 19 December 2015 through 21 December 2015 ; 2015 , Pages 183-190 ; 9781509018932 (ISBN) ; Rabiee, H. R ; Movaghar, A ; Hasheminezhad, R ; Ghalebi, E ; Nazemian, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, motivated by network inference, we introduce a general framework, called LSR-Weighted, to efficiently recover sparse characteristic of links in weighted networks. The links in many real-world networks are not only binary entities, either present or not, but rather have associated weights that record their strengths relative to one another. Such models are generally described in terms of weighted networks. The LSR-Weighted framework uses a newly emerged paradigm in sparse signal recovery named compressive sensing. We study the problem of recovering sparse link vectors with network topological constraints over weighted networks. We evaluate performance of the proposed framework...
The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock
, Article Chinese Journal of Chemical Engineering ; Volume 27, Issue 7 , 2019 , Pages 1699-1707 ; 10049541 (ISSN) ; Riazi, M ; Ayatollahi, S ; Takband, M ; Sharif University of Technology
Chemical Industry Press
2019
Abstract
Carbonated water injection (CWI) is known as an efficient technique for both CO2 storage and enhanced oil recovery (EOR). During CWI process, CO2 moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery...
An efficient stress recovery technique in adaptive finite element method using artificial neural network
, Article Engineering Fracture Mechanics ; Volume 237 , October , 2020 ; Moslemi, H ; Seddighian, M. R ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, an efficient stress recovery technique is presented to estimate the recovered stress field at the nodal points. The feed–forward back–propagation multilayer perceptron (MLP) neural network approach is employed to improve the accuracy of the stress recovery method. An automatic adaptive mesh refinement is performed based on a–posteriori Zienkiewicz–Zhu error estimation method. The proposed technique is employed to recover the stress field accurately in the regions with a high stress gradient where the conventional recovery techniques are not able to improve the stress fields efficiently due to the singular behavior of problem. Finally, several numerical examples are solved to...
Activating solution gas drive as an extra oil production mechanism after carbonated water injection
, Article Chinese Journal of Chemical Engineering ; Volume 28, Issue 11 , 2020 , Pages 2938-2945 ; Ayatollahi, S ; Riazi, M ; Sharif University of Technology
Materials China
2020
Abstract
Enhanced oil recovery (EOR) methods are mostly based on different phenomena taking place at the interfaces between fluid–fluid and rock–fluid phases. Over the last decade, carbonated water injection (CWI) has been considered as one of the multi-objective EOR techniques to store CO2 in the hydrocarbon bearing formations as well as improving oil recovery efficiency. During CWI process, as the reservoir pressure declines, the dissolved CO2 in the oil phase evolves and gas nucleation phenomenon would occur. As a result, it can lead to oil saturation restoration and subsequently, oil displacement due to the hysteresis effect. At this condition, CO2 would act as in-situ dissolved gas into the oil...
Microfluidics experimental investigation of the mechanisms of enhanced oil recovery by low salinity water flooding in fractured porous media
, Article Fuel ; Volume 314 , 2022 ; 00162361 (ISSN) ; Fatemi, M ; Masihi, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Spontaneous imbibition of water from fracture into the matrix is considered as one of the most important recovery mechanisms in the fractured porous media. However, water cannot spontaneously imbibe into the oil-wet rocks and as a result oil won't be produced, unless the capillary pressure barrier between fracture conduits and matrix is overcome. Wettability alteration is known as the main affecting mechanism for low salinity water flooding (LSWF), however, its effectiveness in fractured porous media has been less investigated, especially in the case of possible pore scale displacement mechanisms. In this study, the effectiveness of LSWF (diluted seawater) on oil recovery is compared to the...
Performance analysis of packet loss recovery policies in P2P video streaming
, Article International Journal of Internet Protocol Technology ; Vol. 8, issue. 1 , 2014 , p. 44-53 ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
Abstract
Packet loss recovery is an important part of P2P video streaming networks due to inevitable packet loss in today's internet and interdependency of data units in compressed video streams. In addition, the architecture of P2P streaming networks, in which the data delivered to the receivers through chain of peers, can intensify the impact of the internet packet loss on the quality of perceived video at the receivers. FEC and ARQ are the two most important techniques that can be used to overcome the side effect of the internet packet loss in P2P video streaming networks. Based on these two techniques, different packet loss recovery strategies can be applied in different overlay hops of a given...
Experimental investigation of water alternating CH4-CO 2 mixture gas injection in light oil reservoirs
, Article International Journal of Oil, Gas and Coal Technology ; Vol. 8, issue. 1 , 2014 , p. 31-40 ; Ghazanfari, M. H ; Taghikhani, V ; Badakhshan, A ; Sharif University of Technology
Abstract
This paper studies a WAG process for improving the recovery efficiency in light oil reservoirs. Until now, few references have reported the role of CO2 mole percent on recovery improvement in light oil reservoirs. The injected gas was changed, and the effect of composition changes on performance of core flood experiments were conducted at fixed flow rate. Five series of experiments (varied in methane mole percentages, 0, 25, 50, and 75, 100) were systematically examined. The results indicated that the oil recovery efficiency improved with the increasing of CO2 mole ratio and there was also maximum recovery efficiency in this work. That would be helpful to better understanding the role of CO2...
New surfactant extracted from Zizyphus Spina-Christi for enhanced oil recovery: Experimental determination of static adsorption isotherm
, Article Journal of the Japan Petroleum Institute ; Volume 56, Issue 3 , 2013 , Pages 142-149 ; 13468804 (ISSN) ; Shahri, M. P ; Zargartalebi, M ; Arabloo, M ; Sharif University of Technology
2013
Abstract
A fundamental chemical enhanced oil recovery (EOR) process is surfactant flooding in which the key mechanism is to reduce interfacial tension between oil and the displacing fluid and hence mobilizing the trapped oil. Surfactant loss by adsorption is one of the most important criteria that governs the economics of the surfactant flooding methods. In addition to this, detrimental effects and high price of currently used surfactants cause EOR process so expensive and unfeasible. This study is aimed to introduce a novel kind of plant based surfactant which is extracted from Zizyphus Spina-Christi tree. In addition, equilibrium adsorption behavior of this novel biosurfactant in aqueous solution...
Uranium recovery from UCF liquid waste by nanoporous MCM-41: Breakthrough capacity and elution behavior studies
, Article Research on Chemical Intermediates ; Volume 39, Issue 3 , 2013 , Pages 951-959 ; 09226168 (ISSN) ; Tavakoli, H ; Samadfam, M ; Semnani, F ; Asadi, Z ; Sepehrian, H ; Sharif University of Technology
2013
Abstract
Adsorption and recovery of uranium by nanoporous MCM-41 from aqueous solutions (synthetic solution and uranium conversion facility liquid waste) were investigated by use of a fixed-bed column (1.2 cm diameter and 3.0 cm height). Adsorption was carried out at flow rates 0.2 and 0.5 mL min-1, which correspond to retention times of 10 and 6 min. The maximum breakthrough capacity for uranium ions was achieved by use of nanoporous MCM-41 at the optimum pH of 3.6 and flow rate 0.2 mL min-1 (61.95 μg g-1). The Thomas and Yan models were applied to the experimental data, by use of linear regression, to determine the characteristics of the column for process design. The breakthrough curves calculated...