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An analytical study on the elastic-plastic pure bending of a linear kinematic hardening curved beam
, Article International Journal of Mechanical Sciences ; Volume 144 , 2018 , Pages 274-282 ; 00207403 (ISSN) ; Arghavani, J ; Eskandari, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this study, an analytical solution is presented for elastic-plastic pure bending of a linear kinematic hardening curved beam with rectangular cross section both in monotonic loading and unloading. Compared to exact plane plasticity solution (already reported in the literature in loading) which needs solution of a system of equations, the proposed method is based on the hyperbolic strain distribution on the cross section which yields a simple approximate solution. To this end, we employ Winkler's theory, and assume plane cross sections remain plane after loading proved by the exact elasticity and plasticity solutions for pure bending of curved beams with rectangular cross section. At the...
Roduction of Solar Grade Silicon by Thermal Refining of Industrial Grade Silicon
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
The photovoltaic (PV) industry is in rapid growth and a large supply of PV feedstock materials must be provided to maintain this growth. Since silicon is still the dominant material for the fabrication of solar cells, low-cost solar-grade silicon (SoG-Si) feedstock is demanded. The most cost-effective and direct approach for producing SoG-Si is to purify and upgrade metallurgical-grade silicon. The major impurities in silicon are Al, Fe and Ca. other impurities present are Cu, Ti , Zn, Ni, Cr, Mn, Cd, B and P. In this study The effects of the acid leaching process parameters, including the particle size of silicon, the acid type (HCl, HNO3, H2SO4, and their combination), tmepreture and the...
Nonlinear flexure of Timoshenko–Ehrenfest nano-beams via nonlocal integral elasticity
, Article European Physical Journal Plus ; Volume 135, Issue 8 , 2020 ; Faghidian, S. A ; Asghari, M ; Mohamadi Shodja, H ; Sharif University of Technology
Springer
2020
Abstract
Nonlinear flexural behavior of elastic nano-beams under static loads is investigated in the framework of the Eringen’s nonlocal integral elasticity. The integro-differential and boundary conditions of equilibrium for inflected Timoshenko–Ehrenfest elastic beams with von Kármán nonlinear strains are established by using the minimum total potential energy principle. Eringen’s nonlocal differential law, consequent (but not equivalent) to Eringen’s nonlocal integral convolution, is well established to be inconsistent when applied to bounded domains of nano-mechanics interest. Accordingly, nonlocal integral elasticity formulation is utilized to capture scale effects in the nonlinear flexure of...
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Ali Reza (Supervisor) ; Akhavan, Omid (Supervisor)
Abstract
In photocatalitic activity of titana an effective approach to achieve high charge separation efficiency and high level of sensitivity under visible light is coupling it with another semiconductor with smaller band gap and appropriate banding energy structure. achieving all mentioned above, we used bilayer structure and coupled TiO2 with hematite which its small band gap(Eg ~ 2.1 ev) is sensitive to visible light. Bilayer systems of TiO2/Fe2O3 , Fe2O3/TiO2 were fabricated by sol-gel process and variable parameter was upper layer thickness. The layers were deposited on glass substrate via sol-gel process. The upper layers were prepared in different thicknesses in two ways. First, they...
Fast architecture for decimal digit multiplication
, Article Microprocessors and Microsystems ; Volume 39, Issue 4-5 , June–July , 2015 , Pages 296-301 ; 01419331 (ISSN) ; Valikhani, H ; Timarchi, S ; Tabatabaee Malazi, T ; Sharif University of Technology
Elsevier
2015
Abstract
Abstract BCD digit multiplication module (BDM) is widely used in BCD arithmetic, especially in Decimal Floating-Point (DFP) units. In this paper, we present a new BCD digit multiplication scheme to accelerate this module. Similar to previous articles, our multiplier includes two parts contained binary multiplier and binary to BCD converter. Our contribution towards these modules can successfully overcome the previous BCD digit multipliers. The results indicate 19% hardware acceleration for the proposed multiplier architecture which is comparable to the best previous techniques in UMC 65 nm CMOS standard cells library hardware implementation. Therefore, the proposed BCD digit multiplier is an...
An Analytical Study on the Pure Bending of SMA Curved Beams
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor) ; Arghavani Hadi, Jamal (Supervisor)
Abstract
In this thesis, an analytical solution is presented for pure bending of SMA curved beams with rectangular cross section and both loading and unloading stages are considered. Moreover, by appropriate simplification, its application in elastoplastic pure bending of curved beams made of regular materials is investigated. Elastic-linear kinematic hardening behavior of the material is assumed and both loading and unloading stages are considered. Exact plane plasticity solution of the elastoplastic pure bending of curved beams made of regular materials which exists in loading and is available for rectangular cross section has many unknowns and longsome equations. Therefore, it is difficult to use...
Analysis of porosity distribution of large-scale porous media and their reconstruction by Langevin equation
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 2 , February , 2011 ; 15393755 (ISSN) ; Sahimi, M ; Rasaei, M. R ; Tabar, M. R. R ; Sharif University of Technology
2011
Abstract
Several methods have been developed in the past for analyzing the porosity and other types of well logs for large-scale porous media, such as oil reservoirs, as well as their permeability distributions. We developed a method for analyzing the porosity logs φ(h) (where h is the depth) and similar data that are often nonstationary stochastic series. In this method one first generates a new stationary series based on the original data, and then analyzes the resulting series. It is shown that the series based on the successive increments of the log y(h)=φ(h+δh)-φ(h) is a stationary and Markov process, characterized by a Markov length scale hM. The coefficients of the Kramers-Moyal expansion for...
Attacks on a lightweight mutual authentication protocol under EPC C-1 G-2 standard
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 1 June 2011 through 3 June 2011 ; Volume 6633 LNCS , June , 2011 , Pages 254-263 ; 03029743 (ISSN) ; 9783642210396 (ISBN) ; Alagheband, M. R ; Aref, M. R ; Sharif University of Technology
2011
Abstract
Yeh et al. have recently proposed a mutual authentication protocol based on EPC Class-1 Gen.-2 standard. They claim their protocol is secure against adversarial attacks and also provides forward secrecy. In this paper we show that the proposed protocol does not have cited security features properly. A powerful and practical attack is presented on this protocol whereby the whole security of the protocol is broken. Furthermore, Yeh et al.'s protocol does not assure the untraceabilitiy and backwarduntraceabilitiy attributes. We also will propose our revision to safeguard the Yeh et al.'s protocol against cited attacks
Time-Sharing improves dynamic index coding delay
, Article 2019 Iran Workshop on Communication and Information Theory, IWCIT 2019, 24 April 2019 through 25 April 2019 ; 2019 ; 9781728105840 (ISBN) ; Mojahedian, M. M ; Aref, M. R ; Pakravan, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we show how time-sharing method may reduce transmission delay in the dynamic index coding scenario. We propose a novel time-shared dynamic index coding transmission scheme that achieves the maximum index coding gain for a complete bi-directional side information graph and formulate a constrained optimization problem to tune the transmission scheme for the minimum transmission delay. A closed-form solution is presented for the special case of two-user. We also use analytical and simulation results to provide graphical intuition for the obtained results
Efficiency improvement of a high step up high efficiency converter for photovoltaic applications based on three-state switching cell
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 454-458 ; 9781467344845 (ISBN) ; Zolghadri, M. R ; Hajimoradi, M. R ; Sharif University of Technology
2013
Abstract
This paper suggests methods for improving efficiency of a high step up high efficiency converter based on three state commutation cells. A loss analysis has been performed to identify the source of power loss. Based on this analysis, methods are presented to reduce losses in the most power dissipating elements. These methods include replacing some power diodes with large conduction losses with MOSFETs having small on-state resistance. Efficiency improvement up to %1.25 percent is verified in simulation and experimental results
Locally multipath adaptive routing protocol resilient to selfishness and wormholes
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12 May 2010 through 13 May 2010 ; Volume 6047 LNCS , May , 2010 , Pages 187-200 ; 03029743 (ISSN) ; 9783642128264 (ISBN) ; Pakravan, M. R ; Salmasizadeh, M ; Aref, M. R ; Sharif University of Technology
2010
Abstract
Locally multipath adaptive routing (LMAR) protocol, classified as a new reactive distance vector routing protocol for MANETs is proposed in this paper. LMAR can find an ad-hoc path without selfish nodes and wormholes using a random search algorithm in polynomial-time. Also when the primary path fails, it discovers an alternative safe path if network graph remains connected after eliminating selfish/malicious nodes. The main feature of LMAR to seek safe route free of selfish and malicious nodes in polynomial time is its searching algorithm and flooding stage that its generated traffic is equiloaded compared to single-path routing protocols but its ability to bypass the attacks is much better...
Cooperation within von Willebrand factors enhances adsorption mechanism
, Article Journal of the Royal Society Interface ; Volume 12, Issue 109 , 2015 ; 17425689 (ISSN) ; Mehrbod, M ; Ejtehadi, M. R ; Mofrad, M. R ; Sharif University of Technology
Royal Society of London
2015
Abstract
von Willebrand factor (VWF) is a naturally collapsed protein that participates in primary haemostasis and coagulation events. The clotting process is triggered by the adsorption and conformational changes of the plasma VWFs localized to the collagen fibres found near the site of injury. We develop coarse-grained models to simulate the adsorption dynamics of VWF flowing near the adhesive collagen fibres at different shear rates and investigate the effect of factors such as interaction and cooperativity of VWFs on the success of adsorption events. The adsorption probability of a flowing VWF confined to the receptor field is enhanced when it encounters an adhered VWF in proximity to the...
Liquid-liquid coaxial swirl injector performance prediction using general regression neural network
, Article Particle and Particle Systems Characterization ; Volume 25, Issue 5-6 , 2009 , Pages 454-464 ; 09340866 (ISSN) ; Soltani, M. R ; Ashjaee, M ; Morad, M. R ; Sharif University of Technology
2009
Abstract
A general regression neural network technique was applied to design optimization of a liquid-liquid coaxial swirl injector. Phase Doppler Anemometry measurements were used to train the neural network. A general regression neural network was employed to predict droplet velocity and Sauter mean diameter at any axial or radial position for the operating range of a liquid-liquid coaxial swirl injector. The results predicted by neural network agreed satisfactorily with the experimental data. A general performance map of the liquid-liquid coaxial swirl (LLCS) injector was generated by converting the predicted result to actual fuel/oxidizer ratios. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA
A secure ECC-based privacy preserving data aggregation scheme for smart grids
, Article Computer Networks ; Volume 129 , 2017 , Pages 28-36 ; 13891286 (ISSN) ; Bayat, M ; Pakravan, M. R ; Aref, M. R ; Sharif University of Technology
2017
Abstract
Development of Smart Grid and deployment of smart meters in large scale has raised a lot of concerns regarding customers’ privacy. Consequently, several schemes have been proposed to overcome the above mentioned issue. These schemes mainly rely on data aggregation as a method of protecting users’ privacy from the grid operators. However, the main problem with most of these schemes is the fact that they require a large amount of processing power at the meter side. This, together with the fact that smart meters don't usually have a powerful processor, can cause the unavailability of smart meter data at the required time for operators of the grid, and at the same time prevents smart meters from...
An efficient cooperative message authentication scheme in vehicular ad-hoc networks
, Article 2017 14th International ISC (Iranian Society of Cryptology) Conference on Information Security and Cryptology, ISCISC 2017, 6 September 2017 through 7 September 2017 ; 2018 , Pages 37-41 ; 9781538665602 (ISBN) ; Asaar, M. R ; Salmasizadeh, M ; Aref, M. R ; Sharif University of Technology
2018
Abstract
Real-time applications play a significant role in the area of VANET, and are mainly required for these kinds of networks. On the other hand, when the number of messages received by vehicles increases in the network, then the applied computation load becomes extremely high and consequently, delay on the message authentication process significantly increases. This paper is presented with the aim of introducing a novel cooperative message authentication (CMA) scheme for VANET, the main purpose of which is alleviating the computation load on vehicles while verifying messages by using two-part identity-based signature. The scheme enables vehicles to verify only a limited number of the total...
Neural network prediction of a liquid-liquid coaxial swirl injector performance map
, Article 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 10 January 2005 through 13 January 2005 ; 2005 , Pages 11401-11408 ; Soltani, M. R ; Morad, M. R ; Ashjaee, M ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2005
Abstract
A general regression neural network technique is applied for design optimization of liquid-liquid coaxial swirl injectors. Phase Doppler Anemometry measurements for velocity and SMD distributions for various Reynolds numbers are used to train the neural network to generate the injector's performance map. Excellent agreement between the predicted values and the measurements is obtained. It is observed that by reducing the number of randomly selected training samples to about one third of the number of prediction points, one may reconstruct the velocity field in the extrapolation regime with an accuracy of 93%. Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc....
Velocity field reconstruction in the mixing region of swirl sprays using general regression neural network
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 127, Issue 1 , 2005 , Pages 14-23 ; 00982202 (ISSN) ; Soltani, M. R ; Morad, M. R ; Ashjaee, M ; Sharif University of Technology
2005
Abstract
A general regression neural network technique is proposed for design optimization of pressure-swirl injectors. Phase doppler anemometry measurements for velocity distributions are used to train the neural network. An overall optimized value for the width of the probability is determined. The velocity field in the extrapolation regime is reconstructed with an accuracy of 93%. Excellent agreement between the predicted values and the measurements is obtained. The results indicate that the capability of performing designand optimization studies for pressure-swirl injectors with sufficient accuracy exists by applying modest amount of data in conjunction with an overall optimized value for the...
Turning toxic nanomaterials into a safe and bioactive nanocarrier for co-delivery of DOX/pCRISPR
, Article ACS Applied Bio Materials ; Volume 4, Issue 6 , 2021 , Pages 5336-5351 ; 25766422 (ISSN) ; Bagherzadeh, M ; Ghadiri, A. M ; Fatahi, Y ; Aldhaher, A ; Makvandi, P ; Dinarvand, R ; Jouyandeh, M ; Saeb, M. R ; Mozafari, M ; Shokouhimehr, M ; Hamblin, M. R ; Varma, R. S ; Sharif University of Technology
American Chemical Society
2021
Abstract
Hybrid bioactive inorganic-organic carbon-based nanocomposites of reduced graphene oxide (rGO) nanosheets enlarged with multi-walled carbon nanotubes (MWCNTs) were decorated to provide a suitable space forin situgrowth of CoNi2S4and green-synthesized ZnO nanoparticles. The ensuing nanocarrier supplied π-π interactions between the DOX drug and a stabilizing agent derived from leaf extracts on the surface of ZnO nanoparticles and hydrogen bonds; gene delivery of (p)CRISPR was also facilitated by chitosan and alginate renewable macromolecules. Also, these polymers can inhibit the potential interactions between the inorganic parts and cellular membranes to reduce the potential cytotoxicity....
Development of a wearable measuring system for respiratory plethysmography
, Article Proceedings of the 8th IASTED International Conference on Biomedical Engineering, Biomed 2011, 16 February 2011 through 18 February 2011 ; February , 2011 , Pages 295-299 ; 9780889868663 (ISBN) ; Ramezanzadeh, M ; Narimani, R
2011
Abstract
Assessment of respiratory volume is widely used in clinical application in order to assess the case of respiratory illness, and the progression of the respiratory syndrome. Respiratory plethysmography is used to determine the changes of chest volume to monitor the breathing. A wearable respiration measuring system has been introduced for detection of volume variations of chest. The system consists of a flexible sensor, stretchable cloth and electrical board. The flexible sensor, whose electrical voltage is produced by body movements, is installed inside the shirt and closely contacts the chest. The low frequency components of body movements recorded by the sensor are mainly generated by...
Experimental flow visulization of single swirl spray pattern at various pressure drops
, Article 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2003, Huntsville, AL, 20 July 2003 through 23 July 2003 ; 2003 ; 9781624100987 (ISBN) ; Ashjaee, M ; Soltani, M. R ; Mesbahi, M. H ; Morad, M. R ; Sharif University of Technology
2003
Abstract
An experimental investigation of the flow field of pressure swirl atomizers for different pressure drops is performed. Two experimental methods are employed. For low injection pressures, a visual study is conducted while for higher pressures the velocity components and size of the droplets are measured by using Phase Doppler Anemometer. The spray formation, spray cone angle, and breakup length are visually investigated. Velocity and size of the droplets are measured on a plane of measurement along the axis of the spray so that the properties are carried out in a radial direction as a function of both pressure drop and axial distance from the nozzle. Self-similar mean axial velocity profiles...