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Drop formation from a capillary tube: comparison of different bulk fluid on newtonian drops and formation of newtonian and non-newtonian drops in air using image processing
, Article International Journal of Heat and Mass Transfer ; Volume 124 , 2018 , Pages 912-919 ; 00179310 (ISSN) ; Zadkazemi Derakhshi, A ; Nazari, A ; Firoozabadi, B ; Sharif University of Technology
2018
Abstract
The formation of water drops as a Newtonian fluid and formation of a shear-thinning non-Newtonian fluid, Carboxyl Methyl Cellulose (CMC) from a capillary into different bulk fluids are experimentally investigated. A high speed camera is used to visualize the images of the drops and an image-processing code employed to determine the drop properties from each image. It was found that the properties of the water drops when they are drooped into the liquids bulk fluids such as toluene and n-hexane are almost the same while they differed substantially when they were drooped into the air bulk fluid. It is shown that during the formation of water drop in all three kinds of bulk fluids, the drop...
A constructive genetic algorithm for LBP in face recognition
, Article 3rd International Conference on Pattern Analysis and Image Analysis, IPRIA 2017, 19 April 2017 through 20 April 2017 ; 2017 , Pages 182-188 ; 9781509064540 (ISBN) ; Shouraki, S. B ; Sharif University of Technology
2017
Abstract
LBP coefficients are essential and determine the priority of gray differences. The objectives of this paper are to reveal this and propose a method for finding an optimal priority through the genetic algorithm. On the other hand, the genetic operators such as initialization and cross-over operators, generate invalid coefficients, defective chromosomes. This paper also recommends a rectifying method for correcting defective chromosomes. Results on the FERET and Extended Yale B datasets indicate that the proposed method has markedly higher recognition rates than LBP. © 2017 IEEE
Concurrent learning based finite-time parameter estimation in adaptive control of uncertain switched nonlinear systems
, Article Journal of Control, Automation and Electrical Systems ; Volume 28, Issue 4 , 2017 , Pages 444-456 ; 21953880 (ISSN) ; Yazdani, M ; Sinafar, B ; Sharif University of Technology
Springer New York LLC
2017
Abstract
In this paper, We develop concurrent learning adaptive controller, which uses recorded and current data concurrently for adaptation, to model reference adaptive control (MRAC) of uncertain switched nonlinear systems. In standard MRAC architecture for switched systems, the adaptive update laws are derived based on the gradient descent scheme, but here we developed two novel parameter estimation schemes by using modification terms in adaptation laws in which recorded data are used simultaneously with current data and a triggering time is considered in which a sufficient condition on the linear independence of the recorded data is obtained to guarantee the exponential convergence of tracking...
Synthesis of a new self-supported Mgy(CuxNi0.6-xMn0.4)1-yFe2O4 oxygen carrier for chemical looping steam methane reforming process
, Article International Journal of Hydrogen Energy ; Volume 46, Issue 37 , 2021 , Pages 19397-19420 ; 03603199 (ISSN) ; Soltanieh, M ; Heydarinasab, A ; Maddah, B ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Novel self-supported Mgy(CuxNi0.6-xMn0.4)1-yFe2O4 with (y = 0, 0.05, 0.1, 0.15, and x = 0, 0.15, 0.3, 0.45, 0.6) oxygen carriers (OCs) are synthesized through the co-precipitation method. The synthesized OCs’ properties are characterized by X-ray powder diffraction (XRD), Raman spectra, transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and Thermogravimetric Analysis (TGA). The synthesized OCs are assessed in Chemical Looping Steam Methane Reforming (CL-SMR) process subject to different mesh sizes, reaction temperatures, Steam/Carbon...
Synthesis and optimization of CuxNi0.6-xMn0.4Fe2O4 oxygen carrier for chemical looping steam methane reforming
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; 2021 ; 15567036 (ISSN) ; Heydari Nasab, A ; Soltanieh, M ; Maddah, B ; Sharif University of Technology
Bellwether Publishing, Ltd
2021
Abstract
The self-supported CuxNi0.6-xMn0.4Fe2O4 oxygen carrier (x = 0.1–0.5) is synthesized to be applied in the chemical looping steam methane reforming (CL-SMR) process through the synthesized co-precipitation method. The response surface methodology (RSM) based on the Box–Behnken model is adopted to evaluate the effects of independent variables on the functionality of responses as well as predicting the best response volume. In this method, the variables consisting of reaction temperature (550–700°C), oxygen carrier (OC) loading percentage (0.1–0.5), steam-to-CH4 ratio (S/C), (1.5–3.5), and redox cycles’ count (10–24) and the responses consisting of hydrogen (H2) production yield, CH4 conversion...
Experimental investigation of triton X-100 solution on pulsating heat pipe thermal performance
, Article Journal of Thermophysics and Heat Transfer ; Volume 32, Issue 3 , 2018 , Pages 806-812 ; 08878722 (ISSN) ; Ghasempour, R ; Shafii, M. B ; Ahmadi, M. H ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2018
Abstract
Pulsating heat pipes are cooling devices that are partially filled with working fluid. Working fluid thermophysical properties affect the thermal performance of pulsating heat pipes. In this research, the effect of adding a Triton X-100 surfactant to pure water and using the mixture as a working fluid is investigated experimentally. The results indicate that adding surfactant leads to improvement in the thermal performance of the pulsating heat pipe. In particular, the maximum of the thermal resistance improvement is about 61%, which is attributed to 0.01% surfactant concentration. Higher heat transfer ability is attributed to lower surface tension and the contact angle of the mixture...
How to improve the thermal performance of pulsating heat pipes: A review on working fluid
, Article Renewable and Sustainable Energy Reviews ; Volume 91 , 2018 , Pages 630-638 ; 13640321 (ISSN) ; Ahmadi, M. H ; Ghasempour, R ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Pulsating Heat Pipes (PHPs) are cooling devices that are compact in size and have an ability to transfer heat in low temperature differences. Working fluids strongly affect the thermal performance of PHPs. In this paper, effects of some thermophysical parameters relating to working fluids, such as boiling point, latent heat of vaporization, surface tension, thermal conductivity and dynamic viscosity, are presented based on experimental and numerical studies done in recent years. Addition of nanoparticles to fluids, or making nanofuild, is a new method of improving thermophysical properties of fluids. Recently, many studies are carried out on thermophysical properties of nano-fuild. Results...
Resource-constrained time–cost-quality-energy-environment tradeoff problem by considering blockchain technology, risk and robustness: a case study of healthcare project
, Article Environmental Science and Pollution Research ; Volume 29, Issue 42 , 2022 , Pages 63560-63576 ; 09441344 (ISSN) ; Kargar, B ; Gharehbaghi, A ; Hazrati, H ; Nazari, S ; Amra, M ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Blockchain Technology (BCT) is expanding day by day and is used in all pillars of life and projects. In this research, we survey applicable BCT in project management for the first time. We presented a Resource-Constrained Time–Cost-Quality-Energy-Environment Tradeoff Problem by considering BCT, Risk and Robustness (RCTCQEETPBCTRR) in project scheduling. We utilize hybrid robust stochastic programming, worst case, and Conditional Value at Risk (CVaR) to cope with uncertainty and risks. This type of robustification and risk-averse is presented in this research. A real case study is presented in a healthcare project. We utilize GAMS-CPLEX to solve the model. Finally, we analyze finish time,...
A review on application of nanofluid in various types of heat pipes
, Article Journal of Central South University ; Volume 26, Issue 5 , 2019 , Pages 1021-1041 ; 20952899 (ISSN) ; Ahmadi, M. H ; Sadeghzadeh, M ; Shafii, M. B ; Goodarzi, M ; Sharif University of Technology
Central South University of Technology
2019
Abstract
Nanotechnology is widely used in heat transfer devices to improve thermal performance. Nanofluids can be applied in heat pipes to decrease thermal resistance and achieve a higher heat transfer capability. In the present article, a comprehensive literature review is performed on the nanofluids’ applications in heat pipes. Based on reviewed studies, nanofluids have a high capacity to boost the thermal behavior of various types of heat pipes such as conventional heat pipes, pulsating heat pipes, and thermosyphons. Besides, it is observed that there must be a selected amount of concentration for the high-performance utilization of nanoparticles; high concentration of nanoparticles causes a...
Numerical analysis of photovoltaic solar panel cooling by a flat plate closed-loop pulsating heat pipe
, Article Solar Energy ; Volume 206 , 2020 , Pages 455-463 ; Alhuyi Nazari, M ; Ghasempour, R ; Shafii, M. B ; Akbarzadeh, A. A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Photovoltaic (PV) panels provide a suitable way for the direct conversion of solar energy into electricity. The electrical output and efficiency of PV modules are dependent on working temperature. The present study contributes to investigate the efficiency of utilizing a flat plate closed-loop pulsating heat pipe (CLPHP) to cool down a PV panel in both thermal and economic aspects. Accordingly, a numerical investigation is employed to obtain the surface temperature and electrical gain of the PV panel through four scenarios, including natural cooling without additional equipment, CLPHP-based passive cooling, CLPHP-based active cooling, and a conventional flat plate cooling methods. The...
Experimental investigation of graphene oxide nanofluid on heat transfer enhancement of pulsating heat pipe
, Article International Communications in Heat and Mass Transfer ; Volume 91 , February , 2018 , Pages 90-94 ; 07351933 (ISSN) ; Ghasempour, R ; Ahmadi, M. H ; Heydarian, G ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Pulsating heat pipes (PHPs) are heat transfer devices which are widely utilized in electronic devices and energy systems. Improvement in thermal performance of PHPs will lead to higher heat transfer capacity and enhancement in the efficiency of systems which PHPs are applied. In this study, an experimental investigation was performed on the thermal performance of a pulsating heat pipe by applying graphene oxide nanofluid as working fluid. Four concentrations of graphene oxide (0.25, 0.5, 1, and 1.5 g/lit) in water as base fluid were used in the PHP. Results indicate that adding graphene oxide sheets increased thermal conductivity and viscidity of the base fluid. Moreover, utilizing graphene...
Receivers' positioning in multiple-input multiple-output digital video broadcast-terrestrial-based passive coherent location
, Article IET Radar, Sonar and Navigation ; Volume 6, Issue 7 , 2012 , Pages 603-610 ; 17518784 (ISSN) ; Khalaj, B. H ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
IEEE
2012
Abstract
Using multiple illuminators of opportunity at the transmit side and multiple antennas at the receiver side in a passive coherent location (PCL) scheme is expected to improve the detection performance. However, in such multiple-input multiple-output (MIMO) configuration choosing the position of the receivers is an obstacle that can have significant influence on the resulting performance. In this study, the authors consider the case of digital video broadcast (DVB)-T stations as non-cooperative transmitters and introduce a procedure based on the probability of missed detection to properly place receive antennas in a MIMO digital video broadcasting (DVB)-T based PCL configuration
Experimental investigation of paraffin nano-encapsulated phase change material on heat transfer enhancement of pulsating heat pipe
, Article Journal of Thermal Analysis and Calorimetry ; Volume 137, Issue 5 , 2019 , Pages 1603-1613 ; 13886150 (ISSN) ; Shafii, M. B ; Rezaee Shirin Abadi, A ; Ghasempour, R ; Alhuyi Nazari, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In this study, a mixture of nano-encapsulated phase change materials in water has been used as the working fluid in a pulsating heat pipe in order to investigate its thermal performance. The results of the experiments showed that using the nano-encapsulated paraffin dispersed in water as working fluid improves heat transfer and decreases the thermal resistance of the pulsating heat pipe. On the other hand, among the tested concentrations for nano-encapsulated paraffin, there is an optimal value in which increasing the concentration causes an increase in the thermal resistance of the pulsating heat pipe due to the increased dynamic viscosity of the fluid. Enhancement in the thermal...
An Uplink Packet Scheduling Algorithm in Fixed PMP WiMAX Networks with TDD Frame Structure
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
Worldwide interoperability for Microwave Access (WiMAX) is one of the most dominant cell-based broadband wireless metropolitan access technologies. Packet scheduling algorithm specifies the packet transmission order. In WiMAX standard, packet scheduling algorithm is not defined and its efficient design is left for developers and researchers. The existing researches in the scope of uplink packet scheduling, which is the most challenging packet scheduling scheme, consider only one cell. However the uplink available resources might not be enough when there are many packets that should be scheduled. To solve this problem, we propose an algorithm that uses the load balancing mechanisms that are...
, M.Sc. Thesis Sharif University of Technology ; Shamsaei, Abolfazl (Supervisor)
Abstract
Entrance of air to close water conduits occurs in many ways. This phenomenon makes displeasing effects on water transport structures. Two-phase flows in closed conduits are studied experimentally, numerically and theoretically. Even after decades, due to the complexity of the subject, these studies still require development and reformation. Numerical and theoretical two-phase models are often limited to a special regime of flow."Volume Of Fluid"(VOF) is a model for non-mixing two-phase flows. "Fluent" software uses this model in this field of flows. Volume of fluid is used successfully in some problems like dam break or rising bubbles. Main disadvantage of this model is distribution of the...
A new distributed uplink packet scheduling algorithm in WiMAX newtorks
, Article Proceedings of the 2010 2nd International Conference on Future Computer and Communication, ICFCC 2010, 21 May 2010 through 24 May 2010 ; Volume 2 , May , 2010 , Pages V2232-V2236 ; 9781424458226 (ISBN) ; Beigy, H ; Sharif University of Technology
2010
Abstract
Worldwide interoperability for Microwave Access (WiMAX) is designed to support a wide range of Quality of Service (QoS) requirements for different applications. Unlike the single service networks, a priority based mechanism is needed for specifying the transmission order of packets belonging to different traffic sources according to their QoS characteristics, which is called packet scheduling. In WiMAX standard, packet scheduling algorithm is not defined and its design is left for researchers. In this work, we propose a distributed uplink packet scheduling algorithm. In the proposed algorithm, when uplink capacity cannot satisfy the required resource of connections, according to traffic...
Synthesis of Graphene Oxide-based Polymer Nanocomposites and Investigation of Their Ability in Dye Adsorption
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
In this project, polymer nanocomposites containing graphene oxide were prepared and used for adsorption of several cationic and anionic dyes. In most cases, these nanocomposites were prepared as three-dimentional polymer networks which contain graphene oxide. Nanocomposites with direct grafting of polymer chains onto the surface of graphene oxide were also prepared. Graphene oxide is an oxidized carbonaceous material with unique properties. This material has high surface area, good mechanical strength and various functional groups. Polymeric compounds with different functional groups, structures and properties can be prepared and used. By preparing composites of graphene oxide and polymers,...
Design and Implementation of a Master Robot for a Fracture Reduction Robotic Telesurgery System
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor)
Abstract
Common fracture treatments include open reduction and intramedullary nailing technology. However, these methods have disadvantages such as intraoperative X-ray radiation, delayed union or nonunion and postoperative rotation. Robots provide a novel solution to the aforementioned problems while having new challenges. The robotic system used in the study by providing more precise motion and exerting higher amount of forces makes the operation procedure more straightforward. In a normal operation 300-400 N of extension force would be needed which is fully provided by the surgen which leads to physical his/her (khastegi), by using the robotic system however, this force is simply provided without...
Study on Optimization of the EDC Model for Highly Preheated and Diluted Condition
, M.Sc. Thesis Sharif University of Technology ; Mardani, Amir (Supervisor)
Abstract
Moderate and Intense Low-oxygen Dilution(MILD) is the new member of combustion field. Highly preheated reactants and lowering the oxygen level in MILD combustion has some promising advantages. In this study the MILD burner, Jet-in-Hot-Coflow(JHC), is taken as the main test case. In this Research, Eddy Dissipation Concept combustion model ,introduced by Magnussen et al,is investigated in detail and governing equations are re-extracted. EDC combsution model due to moderate compuational cost in comparison with other combustion model and well prediction ability has drawn attention. Simulations on the Jet-in-Hot-Coflow(JHC) has shown the promising performance of the EDC combustion model. It seems...
Online High-bandwidth Network Application Detection Using Stream Classification
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Trac classication in today’s high-bandwidth networks is challenging, resource consuming, and inaccurate due to the high volume, velocity, and variety aracteristics of the network trac. Trac aracterization and Application identication teniques are widely addressed in the current literature. Due to the massive volume and streaming data in recent years, stream algorithms have been considered by many researers in dierent areas. Online application detection is an issue that has been addressed less frequently in literature. In this thesis, we investigate the performance of 10 dierent stream classication algorithms along with traditional classication algorithms. To generate a robust classier for...