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Evaluation of flapping wing propulsion based on a new experimentally validated aeroelastic model
, Article Scientia Iranica ; Volume 19, Issue 3 , 2012 , Pages 472-482 ; 10263098 (ISSN) ; Aliabadi, S. K ; Sharif University of Technology
2012
Abstract
To evaluate the propulsion system capabilities of a Flapping Micro Air Vehicle (FMAV), a new aeroelastic model of a typical flexible FMAV is developed, utilizing the Euler-Bernoulli torsion beam and quasi steady aerodynamic model. The new model accounts for all existing complex interactions between the mass, inertia, elastic properties, aerodynamic loading, flapping amplitude and frequency of the FMAV, as well as the effects of several geometric and design parameters. To validate the proposed theoretical model, a typical FMAV, as well as an instrumented test stand for the online measurement of forces, flapping angle and power consumption, has been constructed. The experimental results are...
Steady state creep behavior of short fiber composites by mapping, logarithmic functions (MF) and dimensionless parameter (DP) techniques
, Article Archives of Civil and Mechanical Engineering ; Volume 12, Issue 4 , December , 2012 , Pages 455-463 ; 16449665 (ISSN) ; Mondali, M ; Abedian, A ; Sharif University of Technology
2012
Abstract
A new mathematical insight based on logarithmic, polynomial mapping functions (MF), and dimensionless parameter (DP) models is presented for determination of some unknowns in the steady state creep stage of short fiber composites subjected to axial loading. These unknowns are displacement rate in outer surface of the unit cell, shear and equivalent stresses at interface and outer surface of the unit cell, and average axial stress in fiber. Dimensionless parameter technique is presented for determination of displacement rate and equivalent stress in outer surface of the unit cell. However, the polynomial mapping function is presented for determination of average axial stress in fiber. Most...
Nonlinear analysis of chatter in turning process using dimensionless groups
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 37, Issue 4 , July , 2015 , Pages 1151-1162 ; 16785878 (ISSN) ; Jalili, M. M ; Movahhedy, M. R ; Sharif University of Technology
Springer Verlag
2015
Abstract
A new 3-D nonlinear model of chatter vibration in turning process is presented in this paper. The workpiece is modeled as a rotating clamped-free beam which is excited by cutting forces. π-Buckingham theory is used to extract dimensionless parameters for this problem. Using these parameters, non-dimensional equations of motion are developed. An approximate analytical solution of the nonlinear problem is obtained. A study of the influence of different parameters on the stability results is developed. Using these results, turning velocity intervals for stable and unstable cuts are determined
A Power-Law Relationship between Characteristics of Light Source and Quantum Yield in Photocatalytic Systems
, Article Journal of Physical Chemistry C ; Volume 119, Issue 39 , July , 2015 , Pages 22425-22431 ; 19327447 (ISSN) ; Sharif University of Technology
American Chemical Society
2015
Abstract
A new dimensionless parameter, Sh-factor, is introduced by using dimensional analysis and extending the quantum yield definition to show power-law relations among light intensity, light wavelength, distance from light source, concentrations of dye/pollutant and photocatalyst, time, and degradation percent. The Sh-factor has the same equation form for photoactivated remediation systems with particulate and thin-film photocatalysts, and it provides mathematical tools to predict degradation performance of a photocatalytic system. These power-law equations separate simply the operational parameters related to the lamp from semiconductor photocatalyst characteristics. The light scattering and...
Discharge capacity of conventional side weirs in supercritical conditions
, Article 4th European Congress of the International Association of Hydroenvironment engineering and Research, IAHR 2016, 27 July 2016 through 29 July 2016 ; 2016 , Pages 658-664 ; 9781138029774 (ISBN) ; Jalili Ghazizadeh, M. R ; Kabiri Samani, A ; Nekooie, M. A ; Sharif University of Technology
CRC Press/Balkema
2016
Abstract
Side weirs are widely used for level control and flow regulation in hydraulic engineering applications such as irrigation, land drainage, and sewer systems. These hydraulic structures allow a part of the flow to spill laterally when the surface of the flow in the main channel rises above the weir crest. The supercritical flow over a side-weir is a typical case of spatially varied flow with decreasing discharge. This study is aimed at investigating the variations of specific energy along the side-weir using experimental results. Some diagrams have been presented in terms of dimensionless ratio of diverted discharge to total discharge. These diagrams which can be used in the design of side...
Numerical Study and Optimization of Effective Parameters in Freeze Desalination
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor)
Abstract
Freeze desalination as a water refining method has attracted a lot of attention due to its potential in lowering process energy consumption compared to other methods. This method is based on the fact that the dissolved salt is drained from the saline water during its freezing. The current study conducts a parametric study on freezing saline water in a cylindrical container to investigate the impact of geometric and functional factors affecting the desalination quality. This has been done by examining the aforesaid factors in the form of dimensionless parameters such as thermal Grashof number, solutal Grashof number, and Jacob number. In addition, in order to improve the desalination, a novel...
Introducing a dimensionless number as tank selector in hybrid solar thermal energy storage systems
, Article Journal of Mechanical Science and Technology ; Volume 25, Issue 4 , 2011 , Pages 871-876 ; 1738494X (ISSN) ; Zohoor, H ; Sharif University of Technology
Abstract
Using hybrid energy storage system is a method for increasing the storage capability of solar thermal energy. If multiple energy storage devices with complementary performance characteristics are used together, the resulting system will be a 'Hybrid Energy Storage System'. In other words, a Hybrid Energy Storage System (HESS) has several media available for storage at any time. In this way, increase in storable energy is obtained without increasing collectors' area. When there are more than one storage mediums, the system should be able to choose the best medium for storing energy according to the conditions. In the previous works, an optimizer program was used to find the proper medium...
Boundary drag force acting on an impenetrable nano-particle
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 469-473 ; 9780791849170 (ISBN) ; Kebriai, M. H ; Meigounpoury, M. R ; Sharif University of Technology
2010
Abstract
Flow over nano spheres is a fundamental problem encountered in many engineering technical problems and the motion of nano-particles is important in many technical areas, for example nano-organizms motion in aqueous media, super hydrophobic spray for coating materials, nano-capsules for detecting cancer, and additive nano-particles in oil and fuel for automotive engines. In this paper computations are performed to determine the steady flow forces acting on the stationary nano-tube for Reynolds numbers in the range of 0.1
Comparison of the membrane morphology based on the phase diagram using PVP as an organic additive and TiO2 as an inorganic additive
, Article Polymer (United Kingdom) ; Volume 97 , 2016 , Pages 559-568 ; 00323861 (ISSN) ; Safekordi, A ; Tavakolmoghadam, M ; Rekabdar, F ; Hemmati, M ; Sharif University of Technology
Elsevier Ltd
Abstract
The morphology of symmetric and asymmetric membranes obtained by precipitation can be rationalized by thermodynamic and kinetic parameters. Such parameters which the former relates to thermodynamic effect and the latter controls the time of separation of the cast solution film immersing in the non-solvent bath from the glass plate were calculated as dimensionless parameters for further analysis. Phase diagram was used to consider the role of thermodynamic. The kinetic properties of the membranes could be investigated by the rate of mass transfer between solvent and non-solvent. By adding additives to the polymer solution the desire for becoming two phase and also viscosity of the solution...
Damage assessment of RC arch structures using fractal analysis of crack patterns
, Article Nondestructive Characterization and Monitoring of Advanced Materials, Aerospace, Civil Infrastructure, and Transportation XV 2021, 22 March 2021 through 26 March 2021 ; Volume 11592 , 2021 ; 0277786X (ISSN); 9781510640139 (ISBN) ; Khaloo, A ; Sharif University of Technology
SPIE
2021
Abstract
Surface crack patterns can easily show the behavior of concrete elements and structures. However, visual damage inspection performed by experts is a subjective approach and is prone to inaccuracies. The quantification makes this process objective and more reliable. In that regards, the maximum crack width is used as a practical measurement. It has been shown that the crack width is not a good indicator of damage due to its inherent uncertainties; In fact, it might bounce back after unloading. As such, a dimensionless parameter so-called Fractal Dimension has been introduced as a robust index that can quantify the complexity of crack distribution efficiently. The present study aims to...
Sea-level rise impact on fresh groundwater lenses in two-layer small islands
, Article Hydrological Processes ; Vol. 28, issue. 24 , 2014 , p. 5938-5953 ; Mahmoodzadeh, D ; Ataie-Ashtiani, B ; Werner, A. D ; Simmons, C. T ; Sharif University of Technology
Abstract
The fresh groundwater lenses (FGLs) of small islands can be highly vulnerable to climate change impacts, including sea-level rise (SLR). Many real cases of atoll or sandy islands involve two-layer hydrogeological conceptualizations. In this paper, the influential factors that affect FGLs in two-layer small islands subject to SLR are investigated. An analytical solution describing FGLs in circular islands, composed of two geological layers, is developed for the simplified case of steady-state and sharp-interface conditions. An application of the developed model is demonstrated to estimate the FGL thickness of some real-world islands by comparison with existing FGL thickness data. Furthermore,...
Mixed-convection flow of nanofluids and regular fluids in vertical porous media with viscous heating
, Article Industrial and Engineering Chemistry Research ; Volume 50, Issue 15 , 2011 , Pages 9403-9414 ; 08885885 (ISSN) ; Golmakani, A ; Dehkordi, A. M ; Sharif University of Technology
2011
Abstract
In this article, the problem of combined forced and natural convection in a vertical porous channel for both regular fluids and nanofluids has been solved by perturbation and numerical methods, taking into account the influences of viscous heating and inertial force. In this regard, various types of viscous dissipation models, including the Darcy model, the power of drag force model, and the clear fluid compatible model, were considered to account for viscous heating. In addition, the mass flux of nanoparticles was also considered in terms of Brownian and thermophoresis mechanisms. The velocity and temperature distributions of both the regular fluid and nanofluid and the Nusselt number...
Local moment formation in Dirac electrons
, Article Journal of Physics: Conference Series, 14 January 2015 through 15 January 2015 ; Volume 603, Issue 1 , January , 2015 ; 17426588 (ISSN) ; Mahyaeh, I ; Jafari, S. A ; Suzumura Y ; Matsuura H ; Fuseya Y ; Ogata M ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Elemental bismuth and its compounds host strong spin-orbit interaction which is at the heart of topologically non-trivial alloys based on bismuth. These class of materials are described in terms of 4x4 matrices at each v point where spin and orbital labels of the underlying electrons are mixed. In this work we investigate the single impurity Anderson model (SIAM) within a mean field approximation to address the nature of local magnetic moment formation in a generic Dirac Hamiltonian. Despite the spin-mixing in the Hamiltonian, within the Hartree approximation it turns out that the impuritys Green function is diagonal in spin label. In the three dimensional Dirac materials defined over a...
Numerical simulation of collision between two droplets in the T-shaped microchannel with lattice Boltzmann method
, Article AIP Advances ; Volume 6, Issue 11 , 2016 ; 21583226 (ISSN) ; Ebrahimi, S ; Moosavi, A ; Shafii, M. B ; Kowsary, F ; Sharif University of Technology
American Institute of Physics Inc
Abstract
In this study, the Lattice Boltzmann Method (LBM) is used to investigate the deformation of two droplets within microfluidic T-junctions (MFTD). In order to increase the accuracy the two immiscible fluids are modeled using the He-Chen-Zhang model. First, this model is applied to ensure that the surface tension effect existing between the droplets and the continuous fluid is properly implemented in the model. Then the collision and merging of the two droplets within the intersection of a T-shaped microchannel is investigated. For generating droplet formation the effects of relevant dimensionless parameters such as the Reynolds, the Weber numbers as well as a collision parameter affecting the...
Determination of discharge coefficient of triangular labyrinth side weirs with one and two cycles using the nonlinear PLS method
, Article Sustainable Hydraulics in the Era of Global Change - Proceedings of the 4th European Congress of the International Association of Hydroenvironment engineering and Research, IAHR 2016, 27 July 2016 through 29 July 2016 ; 2016 , Pages 653-657 ; 9781138029774 (ISBN) ; Parvaneh, A ; Kabiri Samani, A ; Sharif University of Technology
CRC Press/Balkema
2016
Abstract
Side weirs are hydraulic control structures widely used in irrigation, drainage networks and waste water treatment plants. These structures can be used for adjusting and diverting of flow with minimum energy loss. In spite of many studies were carried out on rectangular side weirs, the studies on oblique and labyrinth side weirs are scarce. In this study, based on the experimental data from more than 210 laboratory tests and through using the multivariable nonlinear partial least square (PLS) method, two nonlinear equations are presented for discharge coefficient CM of triangular labyrinth side weirs with one and two cycles. The obtained empirical equations relating CM with the relevant...
Displacement ratios for structures with material degradation and foundation uplift
, Article Bulletin of Earthquake Engineering ; Volume 17, Issue 9 , 2019 , Pages 5133-5157 ; 1570761X (ISSN) ; Vafaei, A ; Kildashti, K ; Hamidia, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In this paper, combined effects of material degradation, p-delta, and foundation uplift are incorporated in a soil-structure-interaction (SSI) framework to assess seismic response of a single-degree-of-freedom system. The considered phenomenological systems represent a column with a lumped mass on top is placed on a rigid foundation. The foundation is mounted on Winkler springs and dashpots to take account of soil-foundation compliance and material/radiation damping. The springs are tensionless to guarantee that uplift is properly modelled. The model is verified for two specific limit cases with the code and literature to make sure that the model is capable of capturing SSI and foundation...
Splitting dynamics of ferrofluid droplets inside a microfluidic T-junction using a pulse-width modulated magnetic field in micro-magnetofluidics
, Article Soft Matter ; Volume 17, Issue 5 , 2021 , Pages 1317-1329 ; 1744683X (ISSN) ; Dizani, M ; Honarmand, M ; Shafii, M. B ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
Micro-magnetofluidics offers a promising tool for better control over the ferrofluid droplet manipulation which has been vastly utilized in biomedical applications in recent years. In this study, the ferrofluid droplet splitting under an asymmetric Pulse-Width-Modulated (PWM) magnetic field in a T-junction is numerically investigated using a finite volume method and VOF two-phase model. By utilizing the PWM magnetic field, two novel regimes of ferrofluid droplet splitting named as Flowing through the Same Branch (FSB) and Double Splitting (DS) have been observed for the first time. In the FSB regime, the daughter droplets move out of the same microchannel outlet, and in the DS regime, the...
Dynamic analysis of mud loss during overbalanced drilling operation: An experimental study
, Article Journal of Petroleum Science and Engineering ; Volume 196 , 2021 ; 09204105 (ISSN) ; Salmanpour, S ; Zamani, H ; Zivar, D ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Mud filtration happens during an overbalanced drilling operation that causes mud invasion into pores and fractures. The productivity of a formation is significantly affected by the invasion of the mud into the near-wellbore area during the mud loss process. A considerable number of studies have evaluated mud filtration statically; however, a few studies have considered the dynamic behavior of a mud loss process during overbalanced drilling, which results in the inadequate prediction of the mud loss volume and inflicted damage to the formation. In this study, a near-wellbore simulation system (NeWSS) was designed to evaluate the dynamic mud loss behavior using dimensionless parameters and...
Improvement of polymer flooding using in-situ releasing of smart nano-scale coated polymer particles in porous media
, Article Energy Exploration and Exploitation ; Volume 30, Issue 6 , 2012 , Pages 915-940 ; 01445987 (ISSN) ; Ramazani, S. A. A ; Sadeghnejad, S ; Sharif University of Technology
2012
Abstract
The main purpose of this paper is modeling and simulation of in-situ releasing of smart nano-sized core-shell particles at the water-oil interface during polymer flooding. During the polymer flooding process, when these nano-particles reach the water-oil interface, migrate to the oil phase and the hydrophobic layer of them dissolves in this phase. After dissolution of this protective nano-sized layer, the hydrophilic core containing a water-soluble ultra high molecular weight polymer diffuses back into the water phase and with dissolving in this phase, dramatically increases viscosity of flooding water in the neighborhood of the water-oil interface. In this study, two different...
First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases
, Article Journal of Chemical Physics ; Volume 135, Issue 24 , 2011 ; 00219606 (ISSN) ; Metzler, R ; Ejtehadi, M. R ; Sharif University of Technology
2011
Abstract
Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on...