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Wind-tolerant optimal closed loop controller design for a domestic atmospheric research airship
, Article Mechanics Based Design of Structures and Machines ; 2020 ; Pourtakdoust, S. H ; Pazooki, F ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
Airships are inherently sensitive to random atmospheric disturbances that could potentially make their data gathering and observation missions a formidable task. In this context robust closed loop feedback controllers are important. The present study is therefore focused on optimal feedback controller design of an indigenous domestically designed airship (DA) for added robustness against atmospheric disturbances. While the general airship six degrees of freedom (6DoF) governing equations of motion are mathematically nonlinear, one often needs to resort to local linearization methods to benefit from proven linear closed loop controller (CLC) design approaches. In this sense an optimal linear...
Wind-tolerant optimal closed loop controller design for a domestic atmospheric research airship
, Article Mechanics Based Design of Structures and Machines ; Volume 50, Issue 6 , 2022 , Pages 2046-2066 ; 15397734 (ISSN) ; Pourtakdoust, S. H ; Pazooki, F ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Airships are inherently sensitive to random atmospheric disturbances that could potentially make their data gathering and observation missions a formidable task. In this context robust closed loop feedback controllers are important. The present study is therefore focused on optimal feedback controller design of an indigenous domestically designed airship (DA) for added robustness against atmospheric disturbances. While the general airship six degrees of freedom (6DoF) governing equations of motion are mathematically nonlinear, one often needs to resort to local linearization methods to benefit from proven linear closed loop controller (CLC) design approaches. In this sense an optimal linear...
Comparison of ultrasonic wave radiation effects on asphaltene aggregation in toluene-pentane mixture between heavy and extra heavy crude oils
, Article Journal of Energy Resources Technology, Transactions of the ASME ; Volume 134, Issue 2 , 2012 ; 01950738 (ISSN) ; Najafi, I ; Ghazanfari, M. H ; Amani, M ; Sharif University of Technology
2012
Abstract
In this study, it is aimed to compare the efficiency of ultrasonic wave technology on asphaltene flocculation inhibition of crude oils with different American Petroleum Institute (API) gravities. A set of confocal microscopy test is performed and a series of statistical analysis is done. According to the results of this study, there is an optimum radiation time for both crudes at which the viscosity and the flocculation rate of asphaltenic crude oils reduces to its minimum. This optimum appears at later times of radiation for extra heavy oil. Also, it is shown that the rate of changes in the properties measured in this study is sharper for extra heavy crude oil. It could be concluded that...
Stability of Cantilevered Beams Subjected to Random Follower Forces
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In Mechanical systems there is always possibility of statical and dynamical following force. These forces are generated due to aerodynamic pressure, temperature gradient, and jet thrusters. In unstabel systems, if the value of this force exceeds a certaim amount the system becomes unstable. This value is called as critical force. In order to analyse these systems, fisrt of all, the governing dynamic equations are obtained by using the Galerkin-Ritz method. Then, by utilising the modal analysis, these equation are uncoupled. And then, the Ito set of equations are derived. By utilising the Lyapanov method, Ito equations are transfered to another state. and using the fokker-planc equation the...
A System Dynamics Model to Find Optimal Policies for competition and Development of Online Question and Answer Knowledge Markets
, M.Sc. Thesis Sharif University of Technology ; Kianfar, Farhad (Supervisor)
Abstract
Knowledge markets where knowledge transactions take place are today see increasingly expansion by influences of the Internet and the importance of knowledge. A competitive space, thus, has been placed among different enterprises step in knowledge markets. With no exception to this general rule, one of these markets covers online question – answer knowledge market. Google Answers is a proposed website in this area which, although being of interest in recent decades, its activities ended in 2006 for several reasons. Significantly, these markets consist of many factors with interrelated effects on each other and this leads to complexity of systems. Therefore, in order to study these markets, it...
A rapid and convenient synthesis of gem-bis(dithiocarbamate) derivatives from primary aliphatic amines, carbon disulfide, and aromatic aldehydes using boron trifluoride-diethyl etherate
, Article Tetrahedron Letters ; Vol. 55, Issue. 25 , 2014 , Pages 3572-3575 ; ISSN: 00404039 ; Ghiyaei, A. G. G ; Notash, B ; Shayegan, M. H ; Amani, V ; Sharif University of Technology
2014
Abstract
An efficient route for the synthesis of gem-bis(dithiocarbamate) derivatives is developed using dithiocarbamic acid salts generated from primary aliphatic amines and CS2. The method offers high yields, employs mild reaction conditions, and demonstrates excellent functional group compatibility. The structures of the products were confirmed spectroscopically and by X-ray analysis
Investigation of low frequency elastic wave application for fluid flow percolation enhancement in fractured porous media
, Article Petroleum Science and Technology ; Volume 31, Issue 11 , 2013 , Pages 1159-1167 ; 10916466 (ISSN) ; Karimi, R ; Najafi, I ; Ghazanfari, M. H ; Amani, M ; Ghotbi, C ; Sharif University of Technology
2013
Abstract
In recent years, some numerical models have been proposed to investigate the effects of the elastic wave such as ultrasonic on fluid flow behavior in porous media. Nevertheless, none of these models are applicable to the fractured reservoirs, especially when the fluid is a Bingham plastic. In this work, the model proposed by P. P. Iassonov and I. A. Beresnev (2003) for flow under exposure of elastic wave in nonfractured porous media is considered and used for development of a new model of steady state flow of a Bingham plastic fluid in fractured reservoirs. The Kazemi's "block and fracture" model assuming negligible vertical permeability in blocks is considered for modeling. In addition,...
Buckling behavior of composite triangular plates
, Article International Journal of GEOMATE ; Volume 2, Issue 2 , 2012 , Pages 253-260 ; 21862982 (ISSN) ; Heydarnia, E ; Amani, P ; Sharif University of Technology
GEOMATE International Society
2012
Abstract
This paper is to do a brief research on the buckling behavior of composite triangular plates with various edge boundary conditions and in-plane loads. It may be regarded as a right and simple numerical method for the analysis of composite triangular thin plate using the natural Area coordinates. Previous studies on the solution of triangular plates with different boundary conditions were mostly based on the Rayleigh-Ritz principle which is performed in the Cartesian coordinate. In this method, the energy functional of a general triangular plate is derived and the Rayleigh-Ritz method is utilized to derive the governing eigenvalue equation for the buckling problem. The geometry is presented...
A three-winding coupled-inductor high step-up boost converter with an active-clamp circuit
, Article 12th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2021, 2 February 2021 through 4 February 2021 ; 2021 ; 9780738111971 (ISBN) ; Beiranvand, R ; Zolghadri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
A new high step-up boost converter with an active clamp circuit to eliminate voltage spike caused by leakage inductor is introduced in this paper. The introduced power converter has a high voltage gain for variable input voltage from 48V to 80V. Since both main and auxiliary switches turn on with zero voltage switching (ZVS) and all the diodes turn off under zero current switching (ZCS) condition, switching losses and EMI noises are strongly degraded. Therefore, the converter's efficiency is improved significantly. Simulation results show a 96.4% peak efficiency and 95.4% average efficiency. The proposed topology is suitable for low-input-voltage and low-output power applications such as...
A new high step-up interleaved LLC converter
, Article 12th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2021, 2 February 2021 through 4 February 2021 ; 2021 ; 9780738111971 (ISBN) ; Beiranvand, R ; Zolghadri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this study, a new LLC resonant converter for high-voltage high-power applications is introduced. The introduced power converter is a two-phase interleaved full-bridge based that uses a transformer with secondary and tertiary windings to obtain higher output voltage. Zero voltage switching (ZVS) at MOSFETs turn on and zero current switching (ZCS) for all the output diodes at turn off are achieved for a wide range of input voltage (100 V-200 V) and output power (200 W-1500 W) variations. Simulation results show a 95% peak efficiency. © 2021 IEEE
Treatment of wastewatercontaining carbohydrates usingpichia saitoi culture
, Article International Journal of Engineering, Transactions B: Applications ; Volume 17, Issue 3 , 2004 , Pages 209-218 ; 1728-144X (ISSN) ; Yaghmaei, S ; Maghsoodi, V ; Sharif University of Technology
National Research Center of Medical Sciences
2004
Abstract
Treatment of wastewater containing carbohydrates by Pichia saitoi growing on beet molasses was investigated in a well-mixed continuous tank as an alternative to bulking control. The yeast strain that used in this work was isolated from non-alcoholic beverage industrial wastewater, with a view on TOC removal compared with other strains in previous study.In this research the isolated yeast showed high COD and TOC removal at three hydraulic retention times, HRT= 48, 24 and 18 hours.Maximum COD and TOC reductions were obtained at HRT=48 hours, which were 96% and 88%, respectively.The influent COD and TOC were 2500 and 148 mg/1, respectively.The pH maintained for synthetic wastewater was about...
A lightweight mutual authentication scheme for vanets between vehicles and RSUs
, Article ISeCure ; Volume 15, Issue 3 , 2023 , Pages 77-89 ; 20082045 (ISSN) ; Mohajeri, J ; Salmasizadeh, M ; Sharif University of Technology
Iranian Society of Cryptology
2023
Abstract
Vehicular Ad-hoc Networks (VANETs) have emerged as part of Intelligent Transportation Systems (ITS), offering the potential to enhance passenger and driver safety, as well as driving conditions. However, VANETs face significant security challenges and various attacks due to their wireless nature and operation in free space. Mutual authentication between vehicles and RSUs is one of the most, if not the most, critical security requirements in VANETs. In this process, maintaining resource authenticity, data authenticity and preserving users’ privacy, are key concerns. This paper proposes a pseudonym-based authentication scheme for VANETs, built upon existing approaches. The proposed scheme not...
Quantum Modeling of Dynamic Ride-sharing Problem: Development of Quantum Solution Methodologies
, M.Sc. Thesis Sharif University of Technology ; Eshghi, Kourosh (Supervisor)
Abstract
Mathematical modeling and the subsequent development of optimization algorithms for problems have been the core focus of operations research scientists. However, the challenges of solving complex models within an acceptable time frame have consistently fostered creativity in this field. Quantum computing has been proposed as an alternative to binary computing for several decades. In recent years, scientists and researchers in operations research have paid significant attention to utilizing and integrating this logic with optimization. Specifically, quantum variants of many optimization algorithms have been developed; however, more focus needs to be placed on modeling optimization problems...
Modeling the kinetics of asphaltene flocculation in toluene-pentane systems for the case of sonicated crude oils
, Article Scientia Iranica ; Volume 20, Issue 3 , June , 2013 , Pages 611-616 ; 10263098 (ISSN) ; Tavakolian, M ; Najafi, I ; Ghazanfari, M. H ; Taghikhania, V ; Amani, M ; Sharif University of Technology
2013
Abstract
This work is concerned with the monitoring of ultrasound effects on inhibition, as well as the reversible kinetics modeling of asphaltene flocculation in toluene-n-alkane systems, which has been rarely reported in the literature. A crude oil sample was exposed to ultrasound waves, and then the colloidal structural evolutions of flocculated asphaltene particles induced by addition of n-alkane were studied, using a confocal microscopy. Observations confirmed that radiation of ultrasound can change the irreversibility of asphaltene flocculation in crude oil. To interpret the kinetics of asphaltene flock aggregation, the Smoluchowski model was used, and the time dependent size distribution of...
Antioxidant nanomaterials in advanced diagnoses and treatments of ischemia reperfusion injuries
, Article Journal of Materials Chemistry B ; Volume 5, Issue 48 , 2017 , Pages 9452-9476 ; 20507518 (ISSN) ; Habibey, R ; Hajmiresmail, S. J ; Latifi, S ; Pazoki Toroudi, H ; Akhavan, O ; Sharif University of Technology
Royal Society of Chemistry
2017
Abstract
Organ ischemia with inadequate oxygen supply followed by reperfusion (which initiates a complex of inflammatory responses and oxidative stress) occurs in different clinical conditions and surgical procedures including stroke, myocardial infarction, limb ischemia, renal failure, organ transplantation, free-tissue-transfer, cardiopulmonary bypass, and vascular surgery. Even though pharmacological treatments protect against experimental ischemia reperfusion (I/R) injury, there has not been enough success in their application for patient benefits. The main hurdles in the treatment of I/R injury are the lack of diagnosis tools for understanding the complicated chains of I/R-induced signaling...
Determination of 2,4-D in environmental samples by three phases directly suspended LPME combined with HPLC-UV
, Article Analytical Methods ; Volume 3, Issue 10 , 2011 , Pages 2261-2267 ; 17599660 (ISSN) ; Roshan, S ; Asgharinezhad, A. A ; Najafi, E ; Abedi, H ; Tavassoli, N ; Lotfi Zadeh Zhad, H. R ; Sharif University of Technology
2011
Abstract
Experimental design of directly suspended droplet liquid-liquid-liquid microextraction has been used to determine residue of 2,4-D, in environmental water samples. A free suspended droplet of 5.5 μL of receiving phase is delivered to the top-center position of 1-Octanol, which is an immiscible organic solvent, floating on the top of a 2.5 mL aqueous sample while being agitated by a stirring bar to create a mild vortex at the center of the vial. Central composite rotatable design has been used for studying the effect of the parameters, the factors interacting with each other and finding the optimum condition. The chromatographic separation was accomplished on a shim-Pak C18 column using a...
Implementation of SVM framework to estimate PVT properties of reservoir oil
, Article Fluid Phase Equilibria ; Volume 346 , May , 2013 , Pages 25-32 ; 03783812 (ISSN) ; Arabloo, M ; Chamkalani, A ; Amani, M ; Zargari, M. H ; Adelzadeh, M. R ; Sharif University of Technology
2013
Abstract
Through this work, a novel mathematical-based approach was proposed to develop reliable models for calculation of PVT properties of crude oils at various reservoir conditions. For this purpose, a new soft computing approach namely Least Square Support Vector Machine (LSSVM) modeling optimized with Coupled Simulated Annealing (CSA) optimization technique was implemented. The constructed models are evaluated by carrying out extensive experimental data reported in open literature. Results obtained by the proposed models were compared with the corresponding experimental values. Moreover, in-depth comparative studies have been carried out between these models and all other predictive models. The...
Selenium nanoparticles for targeted stroke therapy through modulation of inflammatory and metabolic signaling
, Article Scientific Reports ; Volume 9, Issue 1 , 2019 ; 20452322 (ISSN) ; Habibey, R ; Shokri, F ; Hajmiresmail, S. J ; Akhavan, O ; Mashaghi, A ; Pazoki Toroudi, H ; Sharif University of Technology
Nature Publishing Group
2019
Abstract
Ischemic cerebral stroke is a major cause of death and morbidity. Currently, no neuroprotective agents have been shown to impact the clinical outcomes in cerebral stroke cases. Here, we report therapeutic effects of Se nanoparticles on ischemic stroke in a murine model. Anti-transferrin receptor monoclonal antibody (OX26)-PEGylated Se nanoparticles (OX26-PEG-Se NPs) were designed and synthesized and their neuroprotective effects were measured using in vitro and in vivo approaches. We demonstrate that administration of the biodegradable nanoparticles leads to resolution of brain edema, protection of axons in hippocampus region, and myelination of hippocampal area after cerebral ischemic...
Targeted drug delivery of microbubble to arrest abdominal aortic aneurysm development: a simulation study towards optimized microbubble design
, Article Scientific Reports ; Volume 10, Issue 1 , 2020 ; Ebrahimi, S ; Amani, A ; Fallah, F ; Sharif University of Technology
Nature Research
2020
Abstract
Abdominal aortic aneurysm (AAA) is an irreversible bulge in the artery with higher prevalence among the elderlies. Increase of the aneurysm diameter by time is a fatal phenomenon which will lead to its sidewall rupture. Invasive surgical treatments are vital in preventing from AAA development. These approaches however have considerable side effects. Targeted drug delivery using microbubbles (MBs) has been recently employed to suppress the AAA growth. The present study is aimed to investigate the surface adhesion of different types of drug-containing MBs to the inner wall of AAA through ligand-receptor binding, using fluid-structure interaction (FSI) simulation by using a patient CT-scan...
Effect of material and population on the delivery of nanoparticles to an atherosclerotic plaque: a patient-specific in silico study
, Article Langmuir ; Volume 37, Issue 4 , 2021 , Pages 1551-1562 ; 07437463 (ISSN) ; Shamloo, A ; Barzegar, S ; Forouzandehmehr, M ; Sharif University of Technology
American Chemical Society
2021
Abstract
Coronary artery disease (CAD) is the prevalent reason of mortality all around the world. Targeting CAD, specifically atherosclerosis, with controlled delivery of micro and nanoparticles, as drug carriers, is a very proficient approach. In this work, a patient-specific and realistic model of an atherosclerotic plaque in the left anterior descending (LAD) artery was created by image-processing of CT-scan images and implementing a finite-element mesh. Next, a fluid-solid interaction simulation considering the physiological boundary conditions was conducted. By considering the simulated force fields and particle-particle interactions, the correlation between injected particles at each cardiac...