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Solar radiation on domed roofs
, Article Energy and Buildings ; Volume 41, Issue 11 , 2009 , Pages 1238-1245 ; 03787788 (ISSN) ; Bahadori, M.N ; Sharif University of Technology
2009
Abstract
Solar radiation received and absorbed by four domed roofs was estimated and compared with that of a flat roof. The domed roofs all had the same base areas, and equal to that of the flat roof. One of the roofs considered was the dome of the St. Peter's Church in Rome. Compared with the other roofs considered, this dome had a higher aspect ratio. It was found that all domed roofs received more solar radiation than the flat roof. Considering glazed tiles to cover a selected dome in Iran and the dome of the St. Peter's Church, it was found that the solar radiation absorbed by these roofs is reduced appreciably. In the case of the dome of St. Peter's Church, the amount of radiation absorbed was...
Small-scale thermoelastic damping in micro-beams utilizing the modified couple stress theory and the dual-phase-lag heat conduction model
, Article Journal of Thermal Stresses ; Volume 42, Issue 7 , 2019 , Pages 801-814 ; 01495739 (ISSN) ; Asghari, M ; Bagheri, E ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
In this article, the size-dependent behavior of micro-beams with the thermoelastic damping (TED) phenomenon is studied. The coupled thermoelasticity equations are derived on the basis of the modified couple stress theory (MCST) and dual-phase-lag (DPL) heat conduction model. By solving these coupled equations simultaneously, a closed-form expression for the TED parameter in micro-beams is presented which considers the small-scale effects incorporation. Then, the effect of various parameters on TED in micro-beams, such as micro-beam height, the type of material, boundary conditions, and aspect ratio is investigated. The results show that the influence of utilizing non-classical continuum and...
Small-scale analysis of plates with thermoelastic damping based on the modified couple stress theory and the dual-phase-lag heat conduction model
, Article Acta Mechanica ; Volume 229, Issue 9 , 2018 , Pages 3869-3884 ; 00015970 (ISSN) ; Asghari, M ; Sharif University of Technology
Springer-Verlag Wien
2018
Abstract
Thermoelastic damping (TED) is one of the main energy dissipation mechanisms in structures with small scales. On the other hand, the classical continuum theory is not capable of describing the mechanical behavior of small-scale structures. In this paper, small-scale effects on the thermoelastic damping in microplates are studied. To this end, the coupled governing equations of motion and heat conduction are obtained based on the non-classical continuum theory of the modified couple stress and the dual-phase-lag heat conduction model. By solving these coupled equations, an explicit expression including small-scale effects for calculating TED in microplates is derived. The results are compared...
Size-dependent strain gradient-based thermoelastic damping in micro-beams utilizing a generalized thermoelasticity theory
, Article International Journal of Applied Mechanics ; Volume 11, Issue 1 , 2019 ; 17588251 (ISSN) ; Asghari, M ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2019
Abstract
The small-scale effects on the thermoelastic damping (TED) in Euler-Bernoulli micro-beams is investigated in this study. To this purpose, by utilizing the strain gradient theory (SGT) and the dual-phase-lag (DPL) heat conduction model, the coupled equations of motion and heat conduction are derived. By solving these equations simultaneously and using the Galerkin method, the real and imaginary parts of the frequency and the amount of TED in thin micro-beams are obtained. The results predicted by SGT are compared with those given by the modified couple stress theory (MCST) and the classical continuum theory. In addition, TED is calculated on the basis of energy dissipation approach which...
Size-dependent strain gradient-based thermoelastic damping in micro-beams utilizing a generalized thermoelasticity theory
, Article International Journal of Applied Mechanics ; Volume 11, Issue 1 , 2019 ; 17588251 (ISSN) ; Asghari, M ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2019
Abstract
The small-scale effects on the thermoelastic damping (TED) in Euler-Bernoulli micro-beams is investigated in this study. To this purpose, by utilizing the strain gradient theory (SGT) and the dual-phase-lag (DPL) heat conduction model, the coupled equations of motion and heat conduction are derived. By solving these equations simultaneously and using the Galerkin method, the real and imaginary parts of the frequency and the amount of TED in thin micro-beams are obtained. The results predicted by SGT are compared with those given by the modified couple stress theory (MCST) and the classical continuum theory. In addition, TED is calculated on the basis of energy dissipation approach which...
Simulation of a falling droplet in a vertical channel with rectangular obstacles
, Article European Journal of Mechanics, B/Fluids ; Volume 68 , March-April , 2018 , Pages 108-117 ; 09977546 (ISSN) ; Ebrahimi, S ; Moosavi, A ; Shafii, M. B ; Kowsary, F ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Droplet microfluidic systems have attracted a large amount of research due to their numerous applications in biomedical micro-devices and drug discovery/delivery platforms. One of the most important problems in such systems is to investigate deformation, coalescence, and breakup of droplets within the channel. The present study demonstrates numerical simulation of a falling droplet subject to gravitational force in a channel with embedded rectangular obstacles. The lattice Boltzmann method incorporated using He–Chen–Zhang method for two phase flow is employed. Two rectangular obstacles with inverse aspect ratios are introduced to investigate the mechanism of breakup and deformation of the...
Simulation and control of multidimensional crystallization Processes
, Article Chemical Engineering Communications ; Vol. 201, Issue. 7 , 2014 , pp. 870-895 ; ISSN: 0098-6445 ; Shahrokhi, M ; Sharif University of Technology
Abstract
In this article, solving the population balance equation (PBE) and controlling the final particle size for crystallization problems have been addressed. For solving the general form of multidimensional PBE, a numerical method called conservation element and solution element (CE/SE) has been used. By applying this method to one- and two-dimensional crystallization problems, it has been shown that this technique can handle all types of source terms in the PBE. Model accuracy has been checked with experimental data reported in the literature and also with the analytical solution of PB-type equations. Control of final particle size was formulated in an optimization framework. To obtain a desired...
Sensitivity analysis of torque transmission efficiency of a half-toroidal CVT
, Article 2006 SAE World Congress, Detroit, MI, 3 April 2006 through 6 April 2006 ; 2006 ; 01487191 (ISSN) ; Zohoor, H ; Sharif University of Technology
SAE International
2006
Abstract
In this research a computer model based on elasto hydrodynamic fluid film lubrication is developed in order to calculate the torque transmission efficiency of a half-toroidal CVT variator. Validation of this model is verified by comparing the experimental and the model results. Sensitivity of torque transmission efficiency to eleven parameters is investigated. These parameters are: dimensionless roller curvature, aspect ratio, half cone angle, fluid viscosity index, pressure constant for Roelands model, input rotational velocity, absolute viscosity at atmospheric pressure, Young modulus of disks and power rollers, Poisson ratio of disks and power rollers, number of power rollers and variator...
Seismic evaluation of steel plate shear wall systems considering soil-structure interaction
, Article Soil Dynamics and Earthquake Engineering ; Volume 145 , 2021 ; 02677261 (ISSN) ; Shabanlou, M ; Meghdadi, Z ; Estekanchi, H. E ; Mofid, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study investigates the various effects of Soil-Structure Interaction (SSI) on the seismic behavior of steel frames with Steel Plate Shear Wall (SPSW) lateral resisting systems. Nine steel frames with various aspect ratios are studied under multiple seismic hazard levels. The SPSWs are modeled based on the strip model concept, and the Soil-Structure Systems are simulated using the substructure method. The soil beneath the structure is considered as a homogeneous elastic half-space. The Endurance Time method is exploited for nonlinear dynamic analysis of the fixed-base structures and soil-structure systems. Results indicate that use of fixed-base models leads to the significant...
Seismic assessment of unanchored steel storage tanks by endurance time method
, Article Earthquake Engineering and Engineering Vibration ; Volume 10, Issue 4 , 2011 , Pages 591-603 ; 16713664 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Abstract
Liquid storage tanks are essential structures that are often located in residential and industrial areas; thus an assessment of their seismic performance is an important engineering issue. In this paper, the seismic response of unanchored steel liquid storage tanks is investigated using the endurance time (ET) dynamic analysis procedure and compared to responses obtained for anchored tanks under actual ground motions and intensifying ET records. In most cases, the results from ground motions are properly obtained with negligible differences using ET records. It is observed that uplifting of the tank base, which is closely related to the tank aspect ratio, has the greatest significance in the...
Second law analysis of slip flow heat transfer in annulus microchannel
, Article Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009, 19 July 2009 through 23 July 2009, San Francisco, CA ; Volume 1 , 2009 , Pages 321-330 ; 9780791843567 (ISBN) ; Asgarshamsi, A ; Saidi, M. H ; Sharif University of Technology
Abstract
In the present work, the second law of thermodynamics analysis has been carried out for steady state hydrodynamically and thermally fully developed laminar gas flow in annulus microchannels with asymmetrically heated walls. The rarefaction effects are taken into consideration using first order slip velocity and temperature jump boundary conditions. Viscous heating is also included for both the hot wall and the cold wall cases. Using the velocity distribution obtained in earlier works, the energy equation is solved to get analytically the temperature distribution and consequently to compute the entropy generation rate. The effects of rarefaction and the annulus geometrical aspect ratio on...
Secondary flows, mixing, and chemical reaction analysis of droplet-based flow inside serpentine microchannels with different cross sections
, Article Langmuir ; Volume 37, Issue 17 , 2021 , Pages 5118-5130 ; 07437463 (ISSN) ; Madadelahi, M ; Dizani, M ; Shamloo, A ; Sharif University of Technology
American Chemical Society
2021
Abstract
Chemical bioreactions are an important aspect of many recent microfluidic devices, and their applications in biomedical science have been growing worldwide. Droplet-based microreactors are among the attractive types of unit operations, which utilize droplets for enhancement in both mixing and chemical reactions. In the present study, a finite-volume-method (FVM) numerical investigation is conducted based on the volume-of-fluid (VOF) applying for the droplet-based flows. This multiphase computational modeling is used for the study of the chemical reaction and mixing phenomenon inside a serpentine microchannel and explores the effects of the aspect ratio (i.e., AR = height/width) of...
Scattering of SH-waves by an elliptic cavity/crack beneath the interface between functionally graded and homogeneous half-spaces via multipole expansion method
, Article Journal of Sound and Vibration ; Volume 435 , 2018 , Pages 372-389 ; 0022460X (ISSN) ; Shodja, H. M ; Sharif University of Technology
Academic Press
2018
Abstract
In this study, based on multipole expansion method an analytical treatment is presented for the anti-plane scattering of SH-waves by an arbitrarily oriented elliptic cavity/crack which is embedded near the interface between exponentially graded and homogeneous half-spaces. The cavity is embedded within the inhomogeneous half-space. The boundary value problem of interest is solved by constructing an appropriate set of multipole functions which satisfy (i) the governing equation in each half-space, (ii) the continuity conditions across the interface between the two half-spaces, and (iii) the far-field radiation and regularity conditions. The analytical expressions for the scattered...
Retraction notice to “Numerical study on free convection in a U-shaped CuO/water nanofluid-filled cavity with different aspect ratios using double-MRT lattice Boltzmann” [Therm. Sci. Eng. Progr. 14(2019), 100373]
, Article Thermal Science and Engineering Progress ; Volume 21 , 2021 ; 24519049 (ISSN) ; Hooshmand, P ; Mohammaei, M ; Ross, D ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. Concern has been raised about the identity of the author “David Ross” as the listed institution has denied the affiliation of a person with this name. Further inquiry revealed that the names of the co-authors were added to the revised version of the article without notifying the handling Editor, which is contrary to the journal policy on changes to authorship. Also, the co-authors were not able to provide a reasonable description of their contribution to the article....
Reduction of production rate in y-shaped microreactors in the presence of viscoelasticity
, Article Analytica Chimica Acta ; Volume 990 , 2017 , Pages 121-134 ; 00032670 (ISSN) ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
Abstract
The viscoelasticity effects on the reaction-diffusion rates in a Y-shaped microreactor are studied utilizing the PTT rheological model. The flow is assumed to be fully developed and considered to be created under a combined action of electroosmotic and pressure forces. In general, finite-volume-based numerical simulations are conducted to handle the problem; however, analytical solutions based on the depthwise averaging approach are also obtained for the case for which there is no reaction between the inlet components. The analytical solutions are found to predict accurate results when the width to height ratio is at least 10 and acceptable results for lower aspect ratios. An investigation...
Pure axial flow of viscoelastic fluids in rectangular microchannels under combined effects of electro-osmosis and hydrodynamics
, Article Theoretical and Computational Fluid Dynamics ; 2017 , Pages 1-21 ; 09354964 (ISSN) ; Saidi, M. H ; Ebrahimi, A ; Sharif University of Technology
Abstract
This paper presents an analysis of the combined electro-osmotic and pressure-driven axial flows of viscoelastic fluids in a rectangular microchannel with arbitrary aspect ratios. The rheological behavior of the fluid is described by the complete form of Phan-Thien–Tanner (PTT) model with the Gordon–Schowalter convected derivative which covers the upper convected Maxwell, Johnson–Segalman and FENE-P models. Our numerical simulation is based on the computation of 2D Poisson–Boltzmann, Cauchy momentum and PTT constitutive equations. The solution of these governing nonlinear coupled set of equations is obtained by using the second-order central finite difference method in a non-uniform grid...
Pure axial flow of viscoelastic fluids in rectangular microchannels under combined effects of electro-osmosis and hydrodynamics
, Article Theoretical and Computational Fluid Dynamics ; Volume 32, Issue 1 , 2018 ; 09354964 (ISSN) ; Saidi, M. H ; Ebrahimi, A ; Sharif University of Technology
Springer New York LLC
2018
Abstract
This paper presents an analysis of the combined electro-osmotic and pressure-driven axial flows of viscoelastic fluids in a rectangular microchannel with arbitrary aspect ratios. The rheological behavior of the fluid is described by the complete form of Phan-Thien–Tanner (PTT) model with the Gordon–Schowalter convected derivative which covers the upper convected Maxwell, Johnson–Segalman and FENE-P models. Our numerical simulation is based on the computation of 2D Poisson–Boltzmann, Cauchy momentum and PTT constitutive equations. The solution of these governing nonlinear coupled set of equations is obtained by using the second-order central finite difference method in a non-uniform grid...
Providing Multicolor Plasmonic Patterns with Au@Ag Core-Shell Nanostructures for Visual Discrimination of Biogenic Amines
, Article ACS Applied Materials and Interfaces ; Volume 13, Issue 17 , 2021 , Pages 20865-20874 ; 19448244 (ISSN) ; Ghasemi, F ; Bigdeli, A ; Hormozi Nezhad, M. R ; Sharif University of Technology
American Chemical Society
2021
Abstract
Biogenic amines (BAs) are known as substantial indicators of the quality and safety of food. Developing rapid and visual detection methods capable of simultaneously monitoring BAs is highly desired due to their harmful effects on human health. In the present study, we have designed a multicolor sensor array consisting of two types of gold nanostructures (i.e., gold nanorods (AuNRs) and gold nanospheres (AuNSs)) for the discrimination and determination of critical BAs (i.e., spermine (SM), tryptamine (TT), ethylenediamine (EA), tyramine (TR), spermidine (SD), and histamine (HT)). The design principle of the probe was based on the metallization of silver ions on the surface of AuNRs and AuNSs...
Probabilistic evaluation of 2015 NEHRP soil-structure interaction provisions
, Article Journal of Engineering Mechanics ; Volume 143, Issue 9 , 2017 ; 07339399 (ISSN) ; Mahsuli, M ; Ghannad, M. A ; Sharif University of Technology
Abstract
This paper reveals the consequences of practicing the 2015 National Earthquake Hazards Reduction Program (NEHRP) soilstructure interaction (SSI) provisions, which form the basis of the 2016 edition of the seismic design standard provided by the ASCE. For this purpose, the probability that the practice of SSI provisions, in lieu of fixed-base provisions, increases the ductility demand of the structure computed. It is subsequently investigated whether the NEHRP provisions are indeed an improvement upon the SSI provisions of the current ASCE seismic design standard. To this end, 720 soil-structure systems with different numbers of stories, structural systems, aspect ratios, and foundation...
Primary breakup dynamics and spray characteristics of a rotary atomizer with radial-axial discharge channels
, Article International Journal of Multiphase Flow ; 2018 ; 03019322 (ISSN) ; Farshchi, M ; Ghorbanhoseini, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
An experimental investigation of primary breakup dynamics and spray characteristics of a rotary atomizer with high aspect ratio radial-axial discharge channel is described. A high-resolution shadow imaging technique with pulsed backlight illumination was used for spray visualization. For the rotary atomizer with high aspect ratio discharge channel and radial-axial orientation, visualization showed the occurrence of Centripetal–Coriolis-induced stream-mode injection for all operating conditions. In this mode of injection, a crescent liquid film forms in the channel exit and issues from the orifice as a liquid column or a thin liquid sheet depending on atomizer operating conditions. It was...