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Modification of vogel's inflow performance relationship (IPR) for dual porosity model
, Article Petroleum Science and Technology ; Volume 31, Issue 16 , 2013 , Pages 1633-1646 ; 10916466 (ISSN) ; Gerami, S ; Sharif University of Technology
2013
Abstract
The performance of a solution gas-drive reservoir can be predicted using Vogel inflow performance relation (or IPR), which simply relates the deliverability of a well to bottom-hole pressure and average reservoir pressure. While many studies have shown the success of Vogel-type IPR for single porosity reservoirs, the applicability of this method for naturally fractured reservoirs (NFRs), is under question mainly because of the complex flow behavior in matrix and fracture systems. The present study is undertaken to determine if the relation between NFR flowing wellbore pressure and oil production rate could be described by Vogel's IPR. For this purpose, a synthetic dual porosity fractured...
A Numerical Investigation on Ultimate Strength of Steel Plate Shear Walls Utilizing Various Boundary Frame Elements and Different In-fill Plate Thicknesses
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
In this thesis different steel plate shear walls have been investigated using ABAQUS software. These investigations have been focused on various topics, including both boundary frame elements and also the in-fill plate. The main results have been gathered by utilizing different steel plate thicknesses and different boundary frame elements. In order to achieve a better understanding of the effects of both of these elements, various aspect ratios have also been investigated. Moment of inertia has been noted as the main property of both beams and columns used in SPSW. Comparison of the gained results is noteworthy. They show a variety of changes in the load-displacement diagrams, due to changes...
New expert system for enhanced oil recovery screening in non-fractured oil reservoirs
, Article Fuzzy Sets and Systems ; 2015 ; 01650114 (ISSN) ; Ayatollahi, S ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
Elsevier
2015
Abstract
As the oil production from conventional oil reservoirs is decreasing, oil production through Enhanced Oil Recovery (EOR) processes is supposed to compensate for both the oil production reduction in matured oil reservoirs and the worldwide dramatic increase in oil demand. Therefore, developing a strategy to choose an optimized EOR technique is crucial to find a resolution for production decline in oil reservoirs. A screening tool recommending the most appropriate EOR method is proposed in this study. An expert fuzzy logic system is employed to screen four well-known EOR methods including miscible CO2 injection, miscible HC gas injection, polymer flooding and steam injection based on the...
New expert system for enhanced oil recovery screening in non-fractured oil reservoirs
, Article Fuzzy Sets and Systems ; Volume 293 , 2016 , Pages 80-94 ; 01650114 (ISSN) ; Ayatollahi, S ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
Elsevier
2016
Abstract
As the oil production from conventional oil reservoirs is decreasing, oil production through Enhanced Oil Recovery (EOR) processes is supposed to compensate for both the oil production reduction in matured oil reservoirs and the worldwide dramatic increase in oil demand. Therefore, developing a strategy to choose an optimized EOR technique is crucial to find a resolution for production decline in oil reservoirs. A screening tool recommending the most appropriate EOR method is proposed in this study. An expert fuzzy logic system is employed to screen four well-known EOR methods including miscible CO2 injection, miscible HC gas injection, polymer flooding and steam injection based on the...
Font recognition for Persian optical character recognition system
, Article Iranian Conference on Machine Vision and Image Processing, MVIPVolume 2017-November, 19 April 2018 ; Volume 2017 -November , April , 2018 , Pages 252-257 ; 21666776 (ISSN) ; 9781538644041 (ISBN) ; Veisi, H ; Mirzaie, M ; Mohseni Behbahani, Y ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
Font recognition is one of the pre-processing steps in optical character recognition (OCR) systems that affects on their performance. In this paper two methods are proposed for Persian font recognition. In the first method, Gabor filter is used for feature extraction from the images, then principle component analysis (PCA) applied to reduce feature dimensions and finally, a multi-layer Perceptron (MLP) neural network is used for the classification. In the second techniques, random forest is utilized for recognizing fonts. For evaluation, a dataset includes 10 popular Persian fonts is used. The proposed Gabor-PCA-MLP method has achieved 98.70% of F-measure, and random forest resulted in of...
EOR Screening in Fractured Reservoirs Using Artificial Intelligence Technique
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahabaldin (Supervisor) ; Bozormehry, Ramin (Supervisor)
Abstract
Part1: Since conventional production has continued to fall, oil Production through EOR processes will supply an increasing percentage of the world’s oil demand in future years. Therefore; the importance of choosing the best recovery method becomes increasingly important to decrease the risk and find the best solution to the oil production decline from matured reservoirs. An expert system whose main task is to recommend the most appropriate EOR method will be described. The proposed expert system is utilized fuzzy logic system to screen four well known EOR methods of miscible 〖CO〗_2 injection, miscible HC gas injection, polymer flooding and steam injection based on reservoir and rock...
Control of a non observable double inverted pendulum using a novel active learning method based state estimator
, Article Proceedings - UKSim 4th European Modelling Symposium on Computer Modelling and Simulation, EMS2010, 17 November 2010 through 19 November 2010 ; 2010 , Pages 21-26 ; 9780769543086 (ISBN) ; Bagheri Shouraki, S ; Eghbali, R ; Ghomi Rostami, M ; Sharif University of Technology
2010
Abstract
In this paper a novel fuzzy approach exploiting Active Learning Method is employed in order to estimate the immeasurable states required to control a non-observable double inverted pendulum. Active Learning Method (ALM) is a fuzzy modeling method which exploits Ink Drop Spread (IDS) as its main engine. IDS is a universal fuzzy modeling technique which is very similar to the way human brain processes different phenomena. The ALM system is trained by the data obtained from Linear Quadratic Regulator (LQR) controller. LQR uses an optimal control approach which under certain conditions guarantees robustness. Instead of an expert's knowledge, the LQR controller output is used as a priori...
Recent advances in ageing of 7xxx series aluminum alloys: A physical metallurgy perspective
, Article Journal of Alloys and Compounds ; Volume 781 , 2019 , Pages 945-983 ; 09258388 (ISSN) ; Taheri, A. K ; Taheri, K. K ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Al-Zn-Mg-Cu alloys (7xxx series Al alloys) are extensively used for their superior mechanical and corrosion performance. These properties are microstructure-sensitive and highly dependent on the formation, growth and coarsening of precipitates. To date, a wide variety of ageing procedures have been developed to tailor the evolved microstructures so as to yield a good combination of mechanical capacity and corrosion resistance of 7xxx series Al alloys. Among these methods, isothermal ageing, multi-stage ageing, non-isothermal ageing, retrogression and re-ageing (RRA), and stress ageing (i.e. creep ageing) are the most significant. In the present review, all of these approaches are...
Stiffness and strength estimation of damaged unreinforced masonry walls using crack pattern
, Article Journal of Earthquake Engineering ; Volume 26, Issue 2 , 2022 , Pages 837-856 ; 13632469 (ISSN) ; Beyer, K ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
After an earthquake, the residual stiffness and strength of structural elements are typically estimated based on a qualitative visual inspection of cracks that is prone to error. In this paper a new approach is proposed to automatically estimate the updated stiffness and strength of damaged unreinforced masonry walls by characterization of crack patterns by a mathematical index. It is shown that structural and textural fractal dimensions of a crack pattern reflect the extent of cracking and the type of cracking or crushing, i.e., whether the cracks pass through joints or whether bricks have been damaged and crushed. Using results of six quasi-static cyclic tests on unreinforced brick masonry...
Influence of heat treatment and aging on microstructure and mechanical properties of Mg-1.8Zn-0.7Si-0.4Ca alloy
, Article Materialwissenschaft und Werkstofftechnik ; Volume 50, Issue 2 , 2019 , Pages 187-196 ; 09335137 (ISSN) ; Taheri, K. K ; Taheri, A. K ; Shaeri, M. H ; Sharif University of Technology
Wiley-VCH Verlag
2019
Abstract
In order to optimize the aging treatment of Mg-1.8Zn-0.7Si-0.4Ca alloy, different times and temperatures of solid solution and age hardening were applied to the alloy specimens. Microstructures and mechanical properties of the specimens were investigated using the optical microscopy, field emission scanning electron microscopy equipped with an energy dispersive x-ray spectrometer, x-ray diffraction, hardness, and shear punch tests. The lowest hardness and strength were achieved by solution treating of the alloy at 500 °C for 8 h, presenting the optimal condition for solution treatment of the alloy. The microstructural examinations revealed three different precipitates consisting of CaMgSi,...
The nonlinear diffusion bandwidth: A simple tool for optimizing dispersion maps
, Article Optical Transmission, Switching, and Subsystems IV, Gwangju, 5 September 2006 through 7 September 2006 ; Volume 6353 I , 2006 ; 0277786X (ISSN) ; 0819464481 (ISBN); 9780819464484 (ISBN) ; Fischer, J. K ; Louchet, H ; Jamshidi, K ; Petermann, K ; Sharif University of Technology
2006
Abstract
The concept of a nonlinear transfer function of a fibre-optic communication link is reviewed. Also an approximation of the nonlinear transfer function is introduced, which allows to define an equivalent single-span model of a dispersion-managed multi-span system. In this paper we will show its limits of validity and try to extent these limits by enhancing the theoretical model. In this respect we will discuss the impact of dispersion precompensation and show the influence of residual dispersion per span, number of spans and local dispersion on transmission systems with on-off keying and differential phase-shift keying modulation formats. This approach allows fast assessment of the...
Nickel-based nanosheets array as a binder free and highly efficient catalyst for electrochemical hydrogen evolution reaction
, Article International Journal of Hydrogen Energy ; Volume 47, Issue 82 , 2022 , Pages 34887-34897 ; 03603199 (ISSN) ; Hemmati, K ; Mirabbaszadeh, K ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Hydrogen technology through water electrolyzer systems has attracted a great attention to overcome the energy crisis. So, rationally designed non-noble metal based-electrocatalysts with high activity and durability can lead to high performance water electrolyzer systems and high purity hydrogen generation. Herein, a facile two-step method: hydrothermal and electrodeposition, respectively, are developed to decorate highly porous three-dimensional binder-free structure NiFeO/NiO nanosheets array on Ni foam (NiFeO/NiO/NF) with robust adhesion as a high-performance electrode for Hydrogen Evolution Reaction (HER). The electrodeposition process applied after the initial hydrothermal process...
New operational transconductance amplifiers using current boosting
, Article Midwest Symposium on Circuits and Systems ; 2012 , Pages 109-112 ; 15483746 (ISSN) ; 9781467325264 (ISBN) ; Lazarjan, V. K ; HajSadeghi, K ; Sharif University of Technology
2012
Abstract
New techniques for Class-AB Operational Transconductance Amplifiers (OTAs) are presented. These new techniques are two topologies based on current boosting in class-AB stage which achieve considerable improvement of Slew Rate and Gain-Bandwidth while maintaining the same power consumption as the conventional design. Circuit level analysis and simulation results of proposed circuits in 0.18μm CMOS technology for gain, GBW, slew rate, and settling time are presented to prove the effectiveness of the proposed design method
Ranking of technology transfer barriers in developing countries; case study of Iran's biotechnology industry
, Article IEEE International Conference on Industrial Engineering and Engineering Management, 6 December 2011 through 9 December 2011, Singapore ; 2011 , Pages 1602-1606 ; 21573611 (ISSN) ; 9781457707391 (ISBN) ; Rashvanlouei, K. Y ; Ismail, K ; Sharif University of Technology
2011
Abstract
In this paper, first we shall define a list of technology transfer barriers in the biotechnology field through interviews and literature reviews. Next, we shall categorize them into four major categories of technology, and at last introduce all of the hypotheses on the existence of relationship between each part of technology and failure in the technology transfer process. Questionnaires consisting of two parts were created and handed out to all of the specialists and biotechnology idea-holders in the Iranian National Research center of Biotechnology, Lidco Co, Iran Pastor Institute, Biotechnology Department of University of Tehran, etc. Going on, we've evaluated the factors' validity...
A coupled adjoint formulation for non-cooled and internally cooled turbine blade optimization
, Article Applied Thermal Engineering ; Volume 105 , 2016 , Pages 327-335 ; 13594311 (ISSN) ; Mazaheri, K ; Chaharlang Kiani, K ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Most researches on the application of the adjoint method in turbine blade design are concentrated on the aerodynamic shape optimization without considering the heat transfer to/from the blade material. In this study, the adjoint method is extended to the conjugate heat transfer problems in which the viscous flow field is coupled to heat transfer in the solid region. Introducing a new adjoint variable in the solid domain, a heat adjoint equation is derived which is coupled with the energy adjoint equation in the fluid zone at the fluid/solid interface. The detailed mathematical description associated with the derivation of the heat adjoint equation with corresponding boundary conditions are...
A self-organizing multi-model ensemble for identification of nonlinear time-varying dynamics of aerial vehicles
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 235, Issue 7 , 2021 , Pages 1164-1178 ; 09596518 (ISSN) ; Ahmadi, K. K. A ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
This article presents a novel identification approach which can deal with nonlinear and time-varying characteristics of complex dynamic systems, especially an aerial vehicle in the entire flight envelope. A set of local sub-models are first developed at different operating points of the system, and subsequently a self-organizing multi-model ensemble is introduced to aggregate the outputs of the local models as a single model. The number of employed local models in the proposed multi-model ensemble is optimized using a novel self-organizing approach. Also, wavelet neural networks, which combine both the universal approximation property of neural networks and the wavelet decomposition...
Simple SPR-based colorimetric sensor to differentiate Mg2+ and Ca2+ in aqueous solutions
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 268 , 2022 ; 13861425 (ISSN) ; Salehi, K ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier B.V
2022
Abstract
L-tryptophan functionalized AgNPs were successfully fabricated using a one-pot synthesis method and assessed as a colorimetric probe for rapid and accurate determination of Mg2+ ions. The developed sensor showed a selective response towards Mg2+ with no interference from Ca2+ in the wide concentration range of 1–200 µM. The sensor's response was optimized in the pH range of 9–10, which can be attributed to the protonation of amine groups and their interaction with Mg2+ ions. The stability and selectivity of the sensor were examined in different salt (NaCl) and other metal ions, respectively. The L-tryptophan-AgNPs sensor detected Mg2+ with the limit of detection of 3 µM, which is way lower...
Micro-optoelectromechanical systems accelerometer based on intensity modulation using a one-dimensional photonic crystal
, Article Applied Optics ; Volume 55, Issue 32 , 2016 , Pages 8993-8999 ; 1559128X (ISSN) ; Abedi, K ; Jafari, K ; Gholamzadeh, R ; Sharif University of Technology
OSA - The Optical Society
2016
Abstract
In this paper, we propose what we believe is a novel sensitive micro-optoelectromechanical systems (MOEMS) accelerometer based on intensity modulation by using a one-dimensional photonic crystal. The optical sensing system of the proposed structure includes an air-dielectric multilayer photonic bandgap material, a laser diode (LD) light source, a typical photodiode (1550 nm) and a set of integrated optical waveguides. The proposed sensor provides several advantages, such as a relatively wide measurement range, good linearity in the whole measurement range, integration capability, negligible cross-axis sensitivity, high reliability, and low air-damping coefficient, which results in a wider...
On the formation of intermetallics during the furnace brazing of pure titanium to 304 stainless steel using Ag (30-50%)-Cu filler metals
, Article Materials and Manufacturing Processes ; Volume 25, Issue 11 , 2010 , Pages 1333-1340 ; 10426914 (ISSN) ; Abachi, P ; Dehghani, K ; Pourazarang, K ; Sharif University of Technology
2010
Abstract
In the present work, the effect of brazing pa rameters on the properties of the brazed joint of pure titanium and 304 stainless steel (304SS) was investigated. Three different Ag-Cu filler metals were used, while the temperature and time of brazing were in the range of 800-950°C and 5-45 minutes, respectively. The microstructural observations show that, depending on the brazing conditions, different intermetallic phases such as CuTi2, CuTi, Cu3Ti4, and FeTi were formed at the phases interface. Based on the microstructural observations, a model was developed to characterize the formation of phases at the interfaces and brazed joint. The results show that, while some phases may form during the...
Influence of load history on the force-displacement response of in-plane loaded unreinforced masonry walls
, Article Engineering Structures ; Volume 152 , 2017 , Pages 671-682 ; 01410296 (ISSN) ; Dolatshahi, K. M ; Beyer, K ; Sharif University of Technology
2017
Abstract
Empirical drift capacity models for in-plane loaded unreinforced masonry (URM) walls are derived from results of quasi-static cyclic shear-compression tests. The experimentally determined drift capacities are, however, dependent on the applied demand, i.e., on the loading protocol that is used in the test. These loading protocols differ between test campaigns. The loading protocols applied in tests are also different from the displacement histories to which URM walls are subjected in real earthquakes. In the absence of experimental studies on the effect of loading histories on the wall response, this article presents numerical simulations of modern unreinforced clay block masonry walls that...