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nobakht-juybari--milad
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Experimental Investigation of Using Preformed Particle Gels (PPG) in order to Water Shut Off (WSO)
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahaboden (Supervisor)
Abstract
Excessive water production is one of the common problems during oil recovery that causes the production to decline, the operating cost to increase, and the well to shut in. The heterogeneities such as fractures in the reservoirs causes waterfingering and decrease waterflood efficiency, recovery factor and increase production costs and lead to high watercut. On of the methods used to prevent producing undesireable water from reservoirs is using Preformed Particle Gels (PPGs) that is known as plugging agent. These particles are injected into the hydrocarbon reservoirs and plugged the flow of water and prevent the production of water.In recent years, it has been recognized that the use of...
Optimal sensor placement for source localization in nlos conditions
, Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 435-439 ; 9781538649169 (ISBN) ; Behnia, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
The problem of sensor placement for passive source localization under the non-line of sight signal propagation is considered in this paper. To this end, first we derive the Cramer-Rao lower bound for the time of arrival based source localization under non-line of sight conditions. Then, the optimal arrangement of sensors to achieve this lower bound is obtained in the two important cases with all of the receivers being non line of sight ones in the first case and a combination of line of sight and non-line of sight receivers in the 2nd case. © 2018 IEEE
Synthesis of AgI Nanoparticle in a New SDR
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
In this study, low-cost and simple method of precipitation or reactive crystallization was used to synthesize nanoparticles of silver iodide. For this purpose, the reaction of silver nitrate and potassium iodide along with several surfactants in a rotating disk reactor at ambient temperature and pressure was applied. In addition, the effects of hydrodynamic conditions such as diameter and rotating speed of the disk, feed flow rate, and feed injection location, with some of the effective kinetic parameters in the synthesis such as the concentration of the reactants, type and concentration of the surfactants and free ion ratio and aging time of solutions using dynamic light scattering analysis...
Sensor placement in AOA localization of multiple sources in the presence of distance dependent noise
, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 1233-1238 ; 9781728115085 (ISBN) ; Hamdollahzadeh, M ; Behnia, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we consider the problem of sensor placement for passive source localization under conditions where there are multiple sources and noise measurement is distance dependent. To this end, first we derive the Cramer-Rao bound for the angle of arrival (AOA) based source localization for distance-dependent noise model and existence of multiple sources. Then, the optimal arrangement of sensors to achieve this bound is obtained
Electrical annealing of severely deformed copper: microstructure and hardness
, Article International Journal of Minerals, Metallurgy and Materials ; Volume 24, Issue 10 , 2017 ; 16744799 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
2017
Abstract
Commercial pure copper sheets were severely deformed after primary annealing to a strain magnitude of 2.32 through constrained groove pressing. After induction of an electrical current, the sheets were heated for 0.5, 1, 2, or 3 s up to maximum temperatures of 150, 200, 250, or 300°C. To compare the annealing process in the current-carrying system with that in the current-free system, four other samples were heated to 300°C at holding times of 60, 90, 120, or 150 s in a salt bath. The microstructural evolution and hardness values of the samples were then investigated. The results generally indicated that induction of an electrical current could accelerate the recrystallization process by...
Does the short-term boost of renewable energies guarantee their stable long-term growth? Assessment of the dynamics of feed-in tariff policy
, Article Renewable Energy ; Volume 159 , October , 2020 , Pages 1252-1268 ; Hamed Shakouri, G ; Mashayekhi, A. N ; Kazemi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Feed-in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy could be challenging as it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, it has been illuminated that the early growth of REs capacity could be a temporary boost. And the socio-economic structure of the system will backlash the policy if some social mechanisms are not considered. Social tolerance for paying REs tax and potential investors’ trust emanated from budget-related mechanisms -which have rarely been...
The Effect of Rapid Annealing on Microstructure and Mechanical Properties of Severely Deformed Copper
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Commercial pure copper sheets after primary annealing were severely deformed to amount of 2.32 by Constrained Groove Pressing (CGP) method. These sheets were undergone to electrical current at different heating times of 0.5, 1, 2, and 3 seconds up to four maximum temperatures of 150, 200, 250, and 300 °C without holding time. In order to compare the annealing by electrical current and without electrical current, four other samples were heated to 300 °C with holding times of 60, 90, 120, and 150 seconds in salt bath. Then, samples microstructure evolutions, hardness and shear stress values were investigated. Generally, the results depicted that inducing electrical current can accelerate the...
An S-band 6-bit full 360° phase shifter using wideband quadrature generation with pole-zero manipulation
, Article AEU - International Journal of Electronics and Communications ; Volume 115 , 2020 ; Safarian, A ; Sharif University of Technology
Elsevier GmbH
2020
Abstract
In this paper a 6-bit vector-sum phase shifter with a full 360° variable phase-shift range for S-band has been designed and simulated using standard 180 nm CMOS technology. A new In-phase and Quadrature (I and Q) network to generate quadrature signals with minimum I and Q amplitude mismatch over wide bandwidth is proposed and deployed in the vector sum phase shifter. The designed phase shifter achieves an RMS (root mean square) phase error less than 1.34° and an RMS amplitude error less than 0.43 dB over wide bandwidth of 2 – 4 GHz, resulting in a 6-bit resolution. The gain of phase shifter chain varies from 3 to −6 dB over S-band of 2 – 4 GHz. Moreover the input of phase shifter is widely...
An S-Band CMOS 6-Bit vector-sum phase shifter with low RMS phase error using frequency-to-voltage converter feedforward loop
, Article Journal of Circuits, Systems and Computers ; Volume 29, Issue 3 , 2020 ; Safarian, A ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2020
Abstract
In this paper, a wideband full-360o phase shifter with 6 bits of accuracy has been designed and simulated with minimal root mean square (RMS) phase error. The proposed phase shifter deployed a feed forward path including a frequency-to-voltage converter (FVC) to minimize the mismatch in quadrature generation to eventually reduce the RMS phase error for S-band (2-4GHz) applications. The designed phase shifter in 180nm CMOS technology achieves an RMS phase error in the range of 0.607-1.18? with -50dBm input signal over 2-4GHz frequency band. With lower input signal of -75dBm, the RMS phase error is 0.621-1.34? for 2-4GHz input frequency. The proposed phase shifter shows an RMS amplitude error...
Numerical study of diodicity mechanism in different tesla-type microvalves
, Article Journal of Applied Research and Technology ; Volume 11, Issue 6 , 2013 , Pages 876-885 ; 16656423 (ISSN) ; Shahsavan, M ; Paykani, A ; Sharif University of Technology
2013
Abstract
Microvalve is one of the most important components in microfluidic systems and micropumps. In this paper, threedimensional incompressible flow through a Tesla-type microvalve is simulated using FLUENT computational fluid dynamic package. The flow is laminar and SIMPLE algorithm is used. The second-order upwind method is implemented for discretizing convective terms. The diodicity mechanism is investigated in detail for three different microvalves. Effect of several series Tesla-type microvalves on diodicity is also studied. The numerical analyses reveal that the mechanism of diodicity occurs at the T-junction and side channel. If inlet and outlet channels are eliminated, diodicity can be...
Time-independent quantum circuits with local interactions
, Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 93, Issue 6 , 2016 ; 10502947 (ISSN) ; Kianvash, F ; Nobakht, J ; Karimipour, V ; Sharif University of Technology
American Physical Society
2016
Abstract
Heisenberg spin chains can act as quantum wires transferring quantum states either perfectly or with high fidelity. Gaussian packets of excitations passing through dual rails can encode the two states of a logical qubit, depending on which rail is empty and which rail is carrying the packet. With extra interactions in one or between different chains, one can introduce interaction zones in arrays of such chains, where specific one- or two-qubit gates act on any qubit which passes through these interaction zones. Therefore, universal quantum computation is made possible in a static way where no external control is needed. This scheme will then pave the way for a scalable way of quantum...
Web page classification using social tags
, Article 2009 IEEE International Conference on Social Computing, 29 August 2009 through 31 August 2009 ; Volume 4 , 2009 , Pages 588-593 ; 9780769538235 (ISBN) ; Abolhassani, H ; Rahmani, H ; Nobakht, B ; Sharif University of Technology
2009
Abstract
Social tagging is a process in which many users add metadata to a shared content. Through the past few years, the popularity of social tagging has grown on the web. In this paper we investigated the use of social tags for web page classification: adding new web pages to an existing web directory. A web directory is a general human-edited directory of web pages. It classifies a collection of pages into a wide range of hierarchical categories. The problem with manual construction and maintenance of web directories is the significant need of time and effort by human experts. Our proposed method is based on applying different automatic approaches of using social tags for extending web...
Unitary unraveling for the dissipative continuous spontaneous localization model: application to optomechanical experiments
, Article Physical Review A ; Volume 98, Issue 4 , 2018 ; 24699926 (ISSN) ; Carlesso, M ; Donadi, S ; Paternostro, M ; Bassi, A ; Sharif University of Technology
2018
Abstract
The continuous spontaneous localization (CSL) model strives to describe the quantum-to-classical transition from the viewpoint of collapse models. However, its original formulation suffers from a fundamental inconsistency in that it is explicitly energy nonconserving. Fortunately, a dissipative extension to CSL has been recently formulated that solves such an energy-divergence problem. We compare the predictions of the dissipative and nondissipative CSL models when various optomechanical settings are used and contrast such predictions with available experimental data, thus building the corresponding exclusion plots. © 2018 American Physical Society
On validity assurance of dynamic reconfiguration for component-based programs
, Article Electronic Notes in Theoretical Computer Science ; Volume 159, Issue 1 , 2006 , Pages 227-239 ; 15710661 (ISSN) ; Fekrazad Nobakht, N ; Jalili, R ; Heydarian Dehkordi, F ; Sharif University of Technology
2006
Abstract
Growing the need for long-life and high-available programs, dynamic reconfiguration is going to be an important research issue. Dynamic reconfiguration enables the software systems to change at runtime to decrease their down-time in case of any updating, upgrading or in any changes. Any invalid reconfiguration at runtime may lead programs into invalid states. In this paper, we investigate on validity of dynamic reconfiguration for component-based programs and propose validity conditions for it. We show that the problem of validity assurance in general is undecidable and there is no general-purpose algorithm to verify dynamic reconfiguration validity. To have a computable algorithm for...
Design of a Wide Band phase Shifter Based on Vector Summing
, M.Sc. Thesis Sharif University of Technology ; Atarodi, Mojtaba (Supervisor) ; Safarian, Amin Gasem (Co-Advisor)
Abstract
Phase shifters are commonly used in the implementation of phased-array antenna systems.The function of these systems is highly dependent on the performance of phase shifters. In addition, phase shifter circuits are used in some applications such as antenna test and regulation, power amplifier linearization, and QAM modulator implementation, to name but a handful. In this project, design of phase shifter blocks, as well as limitations of fabrication on silicon substrate, is studied and these blocks are designed for maximum bandwidth and minimum sensitivity based on fabrication characteristics and environmental conditions. Design of a 6-bit phase shifter based on vector-sum method is the...
Degradation behavior of the as-extruded and ECAP-processed Mg-4Zn alloy by Ca addition and hydrothermal coating
, Article Journal of Materials Research and Technology ; Volume 20 , 2022 , Pages 1204-1215 ; 22387854 (ISSN) ; Mohammadi Zerankeshi, M ; Nobakht Farin, F ; Alizadeh, R ; Mahmudi, R ; Sharif University of Technology
Elsevier Editora Ltda
2022
Abstract
Coating is an effective approach to address the high corrosion rate of biodegradable Mg alloys, as their main challenge toward their extensive use. In this regard, it was tried to control the degradation process of an Mg-4Zn alloy by Ca addition, equal channel angular pressing (ECAP), and hydrothermal coating. The obtained results indicated that excellent grain refinement induced by Ca incorporation and ECAP simultaneously, improved both mechanical strength and corrosion resistance of the Mg-based substrate. The achieved grain refinement resulted in a thicker, more compact and integrated coating, where the ECAP-processed Mg-4Zn-0.5Ca alloy exhibited the best coating quality with no...
Metabolomic biomarkers in the diagnosis of non-alcoholic fatty liver disease
, Article Hepatitis Monthly ; Volume 19, Issue 9 , 2019 ; 1735143X (ISSN) ; Ghafourpour, M ; Rezaei Farimani, A ; Gholami, A ; Nobakht Motlagh Ghoochani, B. F ; Sharif University of Technology
Kowsar Medical Publishing Company
2019
Abstract
Background: Nonalcoholic fatty liver disease (NAFLD) is the most abundant chronic liver disorder, because racial and ethnic differences may influence prevalence and severity of NAFLD. Objectives: This metabolomic study was conducted to identify the metabolic biomarkers and determine the mechanism of progress of NAFLD in Iranian patients. Methods: Serum samples were collected from 75 participants (37 healthy controls and 38 patients with NAFLD) after an overnight fast. The metabolome of all samples were determined by nuclear magnetic resonance (NMR) and were compared by multivariate statistical analysis. Results: Totally, 19 metabolomic biomarkers were identified by NMR. Compared to healthy...
Highly efficient of molybdenum trioxide-cadmium titanate nanocomposites for ultraviolet light photocatalytic and antimicrobial application: Influence of reactive oxygen species
, Article Journal of Photochemistry and Photobiology B: Biology ; Volume 191 , 2019 , Pages 75-82 ; 10111344 (ISSN) ; Hosseini, M ; Fakhri, A ; Salari Rad, S ; Hadadi, T ; Nobakht, N ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In the present work we report the enhanced UV light photocatalytic performance of cadmium titanate photocatalyst by MoO 3 for Drug pollutant degradation. The nano photocatalyst sample was synthesized employing the Pechini-ultrasonic-hydrothermal route. Therefore, the nano photocatalyst were characterized by various analytical devices. The wide scan X-ray photoelectron spectral study confirmed the MoO 3 in the CdTiO 3 matrix. The crystallite size calculated with the Debye-Scherrer equation (55.4, 57.0, 61.2 and 63.1 nm for pure CdTiO 3 , MoCdTi-0, MoCdTi-1, and MoCdTi-2 nanocomposites, respectively). SEM micrographs revealed nanowire morphology indicated the crystalline nature of the sample....
Effects of soft marine fouling on wave-induced forces in floating aquaculture cages: Physical model testing under regular waves
, Article Ocean Engineering ; Volume 238 , 2021 ; 00298018 (ISSN) ; Zeinoddini, M ; Aalami Harandi, M. M ; Abi, F. A ; Jadidi, P ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Previous experiments on the fouling/current and fouling/wave interactions were mostly limited to two dimensional (2D) net panels or isolated twines. The current paper deals with the wave-induced forces/moments in three dimensional (3D) physical models of a gravity net-cage. The colonial hydroid Ectopleura larynx, a common fouling organism in the aquaculture industry, was artificially modelled and considered in the current experiments. A clean cage and cages with different fouling lengths were tested under deep-water regular wave trains. The time series of the wave-induced forces/moments in the surge, sway, roll and pitch degrees of freedom were recorded and analysed. The experimental results...
Non-isothermal aging of a high-Zn-containing Al–Zn–Mg–Cu alloy: microstructure and mechanical properties
, Article Materials Science and Technology (United Kingdom) ; 2017 , Pages 1-10 ; 02670836 (ISSN) ; Pourshayan, P ; Nasrollahnezhad, F ; Khani Moghanaki, S ; Kazeminezhad, M ; Logé, R. E ; Nobakht, S ; Sharif University of Technology
2017
Abstract
The non-isothermal aging behaviour of a newly developed Al–Zn–Mg–Cu alloy containing 17 wt-% Zn was investigated. Hardness and shear punch tests demonstrated that during non-isothermal aging, the mechanical properties of the alloy first increased and then decreased. The best properties were obtained in a sample which was non-isothermally aged upto 250°C with heating rate of 20°C min−1, due to the presence of η′/η (MgZn2) phases. This was confirmed by differential scanning calorimetery. After homogenisation, residual eutectic phases remained at triple junctions or in a spherical form. During aging, these phases transformed into rodlike S (Al2CuMg)-phase at 400°C, with sizes ranging from 50 to...