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Mitigating the effect of urban layout on torsion of buildings caused by infill walls
, Article Earthquake and Structures ; Volume 23, Issue 2 , 2022 , Pages 151-168 ; 20927614 (ISSN) ; Tabeshpour, M. R ; Saradj, F. M ; Sharif University of Technology
Techno-Press
2022
Abstract
Torsion is one of the most important causes of building collapse during earthquakes. Sometimes, despite the symmetric form of the building, infill walls disturb the symmetry of the lateral resisting system. The purpose of this research is to investigate the effect of urban layout on developing torsion caused by infill walls. For this purpose, a typological study was conducted based on the conditions of perimeter walls on 364 buildings and then 9 cases were selected. The dimensions of the selected buildings are constant and the conditions of the perimeter walls including facades with openings and cantilevered facades are variable. The selected buildings with 60 different layouts of infill...
Studying effect of entrainment on dynamics of debris flows using numerical simulation
, Article Computers and Geosciences ; Volume 134 , 2020 ; Manzari, M. T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper studies entrainment phenomenon in debris flows using full flow (non-depth-averaged) equations and an Incompressible Smoothed Particle Hydrodynamics (ISPH) method. A viscoplastic constitutive relationship is adopted for both the overlying fluid and bed material. Collapse of a two-dimensional dry granular column on a horizontal bed consisting of entrainable dry granular material is considered as a benchmark problem. The adopted ISPH method for simulation of collapse over rigid and entrainable beds is validated using available numerical and experimental data. To quantify the effects of entrainment on dynamics of flow, the initial aspect ratio of granular column (a) is varied and the...
Fully-coupled mathematical modeling of actomyosin-cytosolic two-phase flow in a highly deformable moving Keratocyte cell
, Article Journal of Biomechanics ; 2017 ; 00219290 (ISSN) ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Interaction between intracellular dynamics and extracellular matrix (ECM) generally occurred into very thin fragment of moving cell, namely lamellipodia, enables all movable cells to crawl on ECM. In fast-moving cells such as fish Keratocytes, Lamellipodia including most cell area finds a fan-like shape during migration, with a variety of aspect ratio function of fish type. In this work, our purpose is to present a novel and more complete two-dimensional continuum mathematical model of actomyosin-cytosolic two-phase flow of a self-deforming Keratocyte with circular spreaded to steady fan-like shape. In the new approach, in addition to the two-phase flow of the F-actin and cytosol, the...
Fully-coupled mathematical modeling of actomyosin-cytosolic two-phase flow in a highly deformable moving Keratocyte cell
, Article Journal of Biomechanics ; Volume 67 , January , 2018 , Pages 37-45 ; 00219290 (ISSN) ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Interaction between intracellular dynamics and extracellular matrix (ECM) generally occurred into very thin fragment of moving cell, namely lamellipodia, enables all movable cells to crawl on ECM. In fast-moving cells such as fish Keratocytes, Lamellipodia including most cell area finds a fan-like shape during migration, with a variety of aspect ratio function of fish type. In this work, our purpose is to present a novel and more complete two-dimensional continuum mathematical model of actomyosin-cytosolic two-phase flow of a self-deforming Keratocyte with circular spreaded to steady fan-like shape. In the new approach, in addition to the two-phase flow of the F-actin and cytosol, the...
Parametric study of the dynamic response of thin rectangular plates traversed by a moving mass
, Article Acta Mechanica ; Volume 223, Issue 1 , September , 2012 , Pages 15-27 ; 00015970 (ISSN) ; Rofooei, F. R ; Sharif University of Technology
2012
Abstract
The governing differential equation of motion of a thin rectangular plate excited by a moving mass is considered. The moving mass is traversing on the plate's surface at arbitrary trajectories. Eigenfunction expansion method is employed to solve the constitutive equation of motion for various boundary conditions. Approximate and exact expressions of the inertial effects are adopted for the problem formulation. In the approximate formulation, only the vertical acceleration component of the moving mass is considered while in the exact formulation all the convective acceleration components are included in the problem formulation as well. Parametric studies are carried out to investigate the...
A novel model for analysis of multilayer graphene sheets taking into account the interlayer shear effect
, Article Meccanica ; Volume 53, Issue 11-12 , 2018 , Pages 3061-3082 ; 00256455 (ISSN) ; Asghari, M ; Sharif University of Technology
Springer Netherlands
2018
Abstract
In this study, a multiplate shear model is developed for dynamic analysis of multilayer graphene sheets with arbitrary shapes considering the interlayer shear effect. By utilizing the model, then some free-vibration analysis is presented. According to the experimental results, the weak interlayer van der Waals interaction cannot maintain the integrity of carbon atoms in adjacent layers. Therefore, it is required that the interlayer shear effect is accounted to study multilayer graphene mechanical behavior. The governing differential equation of motion is derived for the multilayer graphene sheets utilizing a variational approach based on the Kirchhoff plate model. The essential and natural...
Analytical and molecular dynamics simulation approaches to study behavior of multilayer graphene-based nanoresonators incorporating interlayer shear effect
, Article Applied Physics A: Materials Science and Processing ; Volume 124, Issue 2 , 2018 ; 09478396 (ISSN) ; Asghari, M ; Sharif University of Technology
Springer Verlag
2018
Abstract
Analytical and molecular dynamics simulation approaches are used in this paper to study free-vibration behavior of multilayer graphene-based nanoresonators considering interlayer shear effect. According to experimental observations, the weak interlayer van der Waals interaction cannot maintain the integrity of carbon atoms in the adjacent layers. Hence, it is vital that the interlayer shear effect is taken into account to design and analyze multilayer graphene-based nanoresonators. The differential equation of motion and the general form of boundary conditions are first derived for multilayer graphene sheets with rectangular shape using the Hamilton’s principle. Then, by pursuing an...
On the theoretical and molecular dynamic methods for natural frequencies of multilayer graphene nanosheets incorporating nonlocality and interlayer shear effects
, Article Mechanics of Advanced Materials and Structures ; 2021 ; 15376494 (ISSN) ; Taati, E ; Asghari, M ; Sharif University of Technology
Bellwether Publishing, Ltd
2021
Abstract
In this paper, a multiplate nonlocal shear model and molecular dynamic simulations are presented to investigate the effects of interlayer shear and nonlocality on the natural frequencies of multilayer graphene sheets (MLGSs). From one aspect in the optimal design of such structures, the interaction between graphene layers, which can significantly vary the static and dynamic behavior due to lack of solidity of layers stack, should be considered. On the other hand, it is requied that the nonlocality phenomenon which has an effective role in the mechanical analysis of nanostructures is taken into account. To this aim, the equation of motion along with corresponding boundary conditions is...
On the theoretical and molecular dynamic methods for natural frequencies of multilayer graphene nanosheets incorporating nonlocality and interlayer shear effects
, Article Mechanics of Advanced Materials and Structures ; Volume 29, Issue 20 , 2022 , Pages 2873-2883 ; 15376494 (ISSN) ; Taati, E ; Asghari, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this paper, a multiplate nonlocal shear model and molecular dynamic simulations are presented to investigate the effects of interlayer shear and nonlocality on the natural frequencies of multilayer graphene sheets (MLGSs). From one aspect in the optimal design of such structures, the interaction between graphene layers, which can significantly vary the static and dynamic behavior due to lack of solidity of layers stack, should be considered. On the other hand, it is requied that the nonlocality phenomenon which has an effective role in the mechanical analysis of nanostructures is taken into account. To this aim, the equation of motion along with corresponding boundary conditions is...
Development of a penetration model for an erosive long rod considering strength effects of colliding materials
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 225, Issue 4 , August , 2011 , Pages 965-973 ; 09544062 (ISSN) ; Vahedi, K ; Zohoor, H ; Sharif University of Technology
2011
Abstract
In this article a simple penetration model for the terminal ballistic of long rod penetrators is developed. The model is to predict the crater depth of a projectile penetrating into a semi-infinite target. A principle objective was to take an account of strength properties of colliding materials using erosive phenomena. The entire velocity regime from low to hypervelocity is analysed. The effect of the penetrator aspect ratio is also considered in the model. The model developed here is based on the steady-state penetration process and is used to compare with existing experimental measurements. The results of the comparison show very good agreement with experimental investigations of other...
The UV photodetection enhancement of tailored ZnO nanorods by controlling the aspect ratio
, Article Surfaces and Interfaces ; Volume 28 , 2022 ; 24680230 (ISSN) ; Rajabi, M ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier B.V
2022
Abstract
ZnO Nanorods (NRs) are deposited on glass substrate using the hydrothermal method by applying a strategic growth control to improve their aspect ratios. In this research, the aspect ratio was tuned by tailoring the synthesis parameters, including the seed layer annealing temperature, absence/presence of polyethylenimine (PEI) in the growth solution, and the solution preheating process. The effects of these parameters on the morphology, crystal structure, room temperature photoluminescence properties, and current-voltage characteristics were examined by FESEM, XRD, PL, and I-V measurements. It was demonstrated that by varying the seed layer annealing temperature and presence of PEI solution...
The effect of soil-structure interaction on damage index of buildings
, Article Engineering Structures ; Volume 30, Issue 6 , 2008 , Pages 1491-1499 ; 01410296 (ISSN) ; Ali Ghannad, M ; Sharif University of Technology
2008
Abstract
The effect of Soil-Structure Interaction (SSI) on Park and Ang Damage Index in a Bilinear-SDOF model is investigated under seismic loading. This is done through an extensive parametric study. Two non-dimensional parameters are used as the key parameters which control the severity of SSI: (1) a non-dimensional frequency as the structure-to-soil stiffness ratio index and (2) the aspect ratio of the structure. The soil beneath the structure is considered as a homogeneous elastic half space and is modeled using the concept of Cone Models. The system is then subjected to three different earthquake ground motions as the representative motions recorded on different soil conditions. The analysis is...
The effect of soil-structure interaction on hysteretic energy demand of buildings
, Article Structural Engineering and Mechanics ; Volume 24, Issue 5 , 2006 , Pages 641-645 ; 12254568 (ISSN) ; Ghannad, M. A ; Sharif University of Technology
Techno-Press
2006
Abstract
The effect of soil-structure interaction (SSI) on hysteresis energy demand of buildings using an ensemble of alluvium site records was investigated. The structure and the soil were molded separately and then combined to constitute the soil-structure model using the sub-structure method. The key parameters effecting the response of the soil-structure system were found to be a non-dimensional frequency as a representative of structure to soil stiffness ratio; and aspect ratio of the building. It was found that the hysteric energy dissipated in a structure under an earthquake can be highly effected when the stiffness of the soil beneath the structure is altered
Microstructural investigation of semisolid aluminum a356 alloy prepared by the combination of electromagnetic stirring and gas induction
, Article 15th International conference on Semi-Solid Processing of Alloys and Composites, S2P 2018, 22 October 2018 through 24 October 2018 ; Volume 285 SSP , 2019 , Pages 290-295 ; 16629779 (ISSN); 9783035713732 (ISBN) ; Yekani, F ; Aashuri, H ; Sharif University of Technology
Trans Tech Publications Ltd
2019
Abstract
A three phase electromagnetic stirrer was used to agitate aluminum A356 slurry and a dry and oxygen free argon gas was introduced in to the slurry by a porous graphite core at a same time. The prepared semi-solid slurry was then transferred into a metallic mold and was compacted by a drop weight. Results demonstrated a favorable increase in shape factor, decrease in aspect ratio and average diameter size at different intensities of stirring. The intensity of stirring was changed by altering the current passed through the magnetic coil and also bubbling intensity via the porous graphite diffuser. Different time intervals for electromagnetic stirring and gas induction were applied. Agitating...
Novel phenomenological discrete bubble model of freely bubbling dense gas-solid fluidized beds: Application to two-dimensional beds
, Article AIChE Journal ; Volume 58, Issue 11 , January , 2012 , Pages 3306-3317 ; 00011541 (ISSN) ; Molaei Dehkordi, A ; Deen, N. G ; van Sint Annaland, M ; Kuipers, J. A. M ; Sharif University of Technology
2012
Abstract
A phenomenological discrete bubble model has been developed for freely bubbling dense gas-solid fluidized beds and validated for a pseudo-two-dimensional fluidized bed. In this model, bubbles are treated as distinct elements and their trajectories are tracked by integrating Newton's equation of motion. The effect of bubble-bubble interactions was taken into account via a modification of the bubble velocity. The emulsion phase velocity was obtained as a superposition of the motion induced by individual bubbles, taking into account bubble-bubble interaction. This novel model predicts the bubble size evolution and the pattern of emulsion phase circulation satisfactorily. Moreover, the effects...
A numerical study of reactive pollutant dispersion in street canyons with green roofs
, Article Building Simulation ; Volume 11, Issue 1 , February , 2018 , Pages 125-138 ; 19963599 (ISSN) ; Afshin, H ; Farhanieh, B ; Sharif University of Technology
Tsinghua University Press
2018
Abstract
Roof greening is a new technique for improvement of outdoor thermal environment which influences air quality through its impacts on thermal and flow field. In order to examine effects of green roofs on reactive pollutant dispersion within urban street canyons, a computational fluid dynamics (CFD) model was employed which contained NO-NO2-O3 photochemistry and energy balance models. Simulations were performed for street canyons with different aspect ratios (H/W) of 0.5, 1.0, and 2.0 such that leaf area density (LAD) of green roofs changed. It was found that roof greening led distribution of pollutants to alter for H/W = 0.5 and 1.0 cases in such a manner that their averaged concentrations had...
Penetration of elliptical liquid jets in low-speed crossflow
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 141, Issue 1 , 2019 ; 00982202 (ISSN) ; Khosrobeygi, H ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
Trajectory and penetration of elliptical liquid jets emerged into a low-speed crossflow of air are studied. The jets are introduced to the crossflow at different momentum ratios ranging from 1 to 300. The images are analyzed to obtain the trajectories of the outer boundary of the jets for two different aspect ratios. An empirical correlation is proposed for the present injector geometries and for the range of momentum ratio, Weber, and Reynolds numbers used in this study. Finally, a theoretical model for the trajectory of the liquid column for an initially elliptical liquid emerging into a crossflow is presented, and the associated drag coefficients are obtained for a precise trajectory...
Penetration of elliptical liquid jets in low-speed crossflow
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 141, Issue 1 , 2019 ; 00982202 (ISSN) ; Khosrobeygi, H ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
Trajectory and penetration of elliptical liquid jets emerged into a low-speed crossflow of air are studied. The jets are introduced to the crossflow at different momentum ratios ranging from 1 to 300. The images are analyzed to obtain the trajectories of the outer boundary of the jets for two different aspect ratios. An empirical correlation is proposed for the present injector geometries and for the range of momentum ratio, Weber, and Reynolds numbers used in this study. Finally, a theoretical model for the trajectory of the liquid column for an initially elliptical liquid emerging into a crossflow is presented, and the associated drag coefficients are obtained for a precise trajectory...
Axis-switching and breakup of rectangular liquid jets
, Article International Journal of Multiphase Flow ; Volume 126 , May , 2020 ; Nasiri, M ; Amini, G ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The behavior of low-speed liquid jets emerging from rectangular orifices into a quiescent air is studied numerically. After ejection, the rectangular cross-section transforms into an elliptical form along the jet and while axis-switching includes elliptical cross-sections only, the rectangular shape never establishes again. The optimum wavenumber, corresponding to the most dominant wave, is found to be greater in orifices with higher aspect ratios and, as a result, breakup length of the jet will be shorter. The breakup length decreases exponentially with the initial amplitude of disturbances. Moreover, it is observed that the form of final breakup leads to elimination of the satellite...
Numerical modeling of instability and breakup of elliptical liquid jets
, Article AIAA Journal ; Volume 58, Issue 6 , June , 2020 , Pages 2442-2449 ; Nasiri, M ; Amini, G ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2020
Abstract
Numerical simulations are performed to provide an in-depth insight into the effect of instabilities on liquid jets discharging from elliptical orifices. The axis-switching phenomenon and breakup are simulated and characterized under the effect of disturbances imposed at the nozzle exit. The simulations are based on the volume of fluid approach and an adaptive meshing. A range of orifice aspect ratios from 1 to 4 at the Rayleigh breakup regime is considered. The evolution of the jet cross section and axis switching under the influence of disturbances is compared with that of nonperturbed elliptical jets. It is found that the axis-switching repetition and breakup length exponentially decrease...