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    Confinement dynamics of a semiflexible chain inside nano-spheres

    , Article Journal of Chemical Physics ; Volume 139, Issue 4 , 2013 ; 00219606 (ISSN) Fathizadeh, A ; Heidari, M ; Eslami Mossallam, B ; Ejtehadi, M. R ; Sharif University of Technology
    2013
    Abstract
    We study the conformations of a semiflexible chain, confined in nano-scaled spherical cavities, under two distinct processes of confinement. Radial contraction and packaging are employed as two confining procedures. The former method is performed by gradually decreasing the diameter of a spherical shell which envelopes a confined chain. The latter procedure is carried out by injecting the chain inside a spherical shell through a hole on the shell surface. The chain is modeled with a rigid body molecular dynamics simulation and its parameters are adjusted to DNA base-pair elasticity. Directional order parameter is employed to analyze and compare the confined chain and the conformations of the... 

    A simplified model for the flow inside cascade impactor

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 7 A , November , 2013 ; 9780791856314 (ISBN) Mehr, S. M. N ; Sohrabi, S ; Falsafi, P ; Gorji, P ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2013
    Abstract
    In this paper we developed a new mathematical model for the flow inside cascade impactors and via this simplified model, we determined the particle size distribution by a fast and low cost computational method. Using cascade impactors for determining the particle size distribution, one can use comprehensive CFD methods to fully simulate the particle traces. Although the results from those CFD analyses can be very accurate, usually that is not a time and cost efficient routine. In contrast, we showed that by using our proposed calculation we can estimate the particle size distribution very fast and yet with the slight error -comparing to the results from CFD method. Cascade impactors are... 

    Numerical investigation of droplets breakup in a microfluidic T-junction

    , Article Applied Mechanics and Materials ; Volume 110-116 , 2012 , Pages 3269-3277 ; 16609336 (ISSN) ; 9783037852620 (ISBN) Bedram, A ; Moosavi, A ; Int. Assoc. Comput. Sci. Inf. Technol. (IACSIT) ; Sharif University of Technology
    2012
    Abstract
    A Volume of Fluid (VOF) method is used to stdy the breakup of droplets in T-junction geometries. Symmetric T-junctions, which are used to produce equal size droplets and have many applications in pharmacy and chemical industries, are considered. Two important factors namely "breakup time" and "breakup length" that can improve the performance of these systems have been introduced. In addition a novel system which consists of an asymmetric T-junction is proposed to produce unequal size droplets. The effects of the channel width ratio and the capillary number on the size and length of the generated droplets and also the time of the generation have been studied and discussed. For simulation the... 

    Experimental investigation on turbulence intensity reduction in subsonic wind tunnels

    , Article Aerospace Science and Technology ; Volume 15, Issue 2 , 2011 , Pages 137-147 ; 12709638 (ISSN) Ghorbanian, K ; Soltani, M. R ; Manshadi, M. D ; Sharif University of Technology
    Abstract
    Experiments are performed to evaluate the impact of trip wires on the turbulence intensity in a few low speed wind tunnels. Trip wires of different sizes are installed at different positions in the contraction section of four different wind tunnels and measurements are made at various free stream velocities. The results indicate that the pressure distributions are altered compared to the clean condition. Trip wires move the adverse pressure gradient toward the inlet of the contraction section. Consequently, the turbulence intensity in the test section of the wind tunnels is reduced and the flow uniformity is improved considerably. Frequency and statistical analysis are performed and the... 

    Simulation of natural convection of nanofluids at high rayleigh numbers: A two-component lattice Boltzmann study

    , Article Computational Thermal Sciences ; Volume 8, Issue 1 , 2016 , Pages 31-47 ; 19402503 (ISSN) Hosseini Abadshapoori, M ; Saidi, M. H ; Sharif University of Technology
    Begell House Inc 
    Abstract
    In this research, the effect of using nanoparticles on the Nusselt number in the natural convection at high Rayleigh numbers has been investigated. A two-component multiple relaxation times lattice Boltzmann code has been developed to investigate the natural convection of nanofluids in a 2D square enclosure. Three main forces, namely, buoyancy, drag, and Brownian forces are included to consider the interactions of the components. The potential force is also added to the model for the interactions among nanoparticles. The effects of Ra number, volume fraction of nanoparticles (ϕ), and size of nanoparticles (λ) have been investigated for two nanofluids (CuO-water and TiO2-water). Five... 

    Cellular model of electroporated tissue for ultrasound RF data analysis

    , Article 2009 International Conference on Advances in Computational Tools for Engineering Applications, ACTEA 2009, Beirut, 15 July 2009 through 17 July 2009 ; 2009 , Pages 652-655 ; 9781424438341 (ISBN) Dashti, A ; Zahedi, E ; National Instruments; MSC Software; Pro Mech ; Sharif University of Technology
    2009
    Abstract
    Electroporation is permeabilization of the cell membrane, caused by an external electric field. Because of minimal thermal effects and minimal disturbance caused to tissue vasculature electroporation is becoming one of the methods of choice in tumor therapy. There has been no report indicating that reversible electroporation can be detected by ultrasound. In this work a cellular model for monitoring the electroporation process b; ultrasound RF signals is proposed. The density of aqueous pores with different sizes was found by applying the asymptotic model of electroporation and Smoluchowski equation. The cellular model was send to an ultrasound simulation program where pores were modeled by... 

    On the applicability range of Cassie–Baxter and Wenzel equation: a numerical study

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 10 , 2019 ; 16785878 (ISSN) Azadi Tabar, M ; Barzegar, F ; Ghazanfari, M. H ; Mohammadi, M ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this study, the range of applicability for Cassie–Baxter and Wenzel equations for estimating apparent contact angle on rough surfaces is numerically discussed. To do this, circular drops with different sizes are simulated on rough surfaces with a square pillar pattern and randomly distributed cylindrical pillar. With the aid of numerical method, the local surface fraction, local length fraction and local roughness factor for drops with different sizes on the surface are computed. Then, the global surface fraction and global roughness factor have been compared with the local surface fraction and local roughness factor, respectively. Local surface and local length fractions, as well as... 

    Study on mechanical properties of ternary blended concrete containing two different sizes of nano-SiO2

    , Article Composites Part B: Engineering ; Volume 167 , 2019 , Pages 20-24 ; 13598368 (ISSN) Nazerigivi, A ; Najigivi, A ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    The aim of this study was to investigate the influences of combination of the two different SiO2 nanoparticles (15 nm and 80 nm) on compressive, flexural and tensile strength of ternary blended concrete. SiO2 nanoparticles with two different sizes of 15 and 80 nm have been used as a partial cement replacement by 0.5, 1.0, 1.5 and 2.0 wt.% in 16 different proportions of mixture followed by curing in lime solution for 7, 28 and 90 days. The results indicate that in all curing ages in lime solution specimens with 2.0% of 15 nm plus 1.5% of 80 nm cement replacement achieved higher mechanical properties. The continuous cement paste with the lowest delicate zones might be due to the fact of quick... 

    Localizing exception faults in Android applications

    , Article Scientia Iranica ; Volume 26, Issue 3 D , 2019 , Pages 1567-1588 ; 10263098 (ISSN) Mirzaei, H ; Heydarnoori, A ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    In software programs, most of the time, there is a chance for occurrence of faults in general, and exception faults in particular. Localizing those pieces of code that are responsible for a particular fault is one of the most complicated tasks, and it can produce incorrect results if done manually. Semi-automated and fully-automated techniques have been introduced to overcome this issue. However, despite recent advances in fault localization techniques, they are not necessarily applicable to Android applications because of their special characteristics such as context-awareness, use of sensors, being executable on various mobile devices, limited hardware resources, etc. To this aim, in this... 

    Localizing exception faults in Android applications

    , Article Scientia Iranica ; Volume 26, Issue 3 D , 2019 , Pages 1567-1588 ; 10263098 (ISSN) Mirzaei, H ; Heydarnoori, A ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    In software programs, most of the time, there is a chance for occurrence of faults in general, and exception faults in particular. Localizing those pieces of code that are responsible for a particular fault is one of the most complicated tasks, and it can produce incorrect results if done manually. Semi-automated and fully-automated techniques have been introduced to overcome this issue. However, despite recent advances in fault localization techniques, they are not necessarily applicable to Android applications because of their special characteristics such as context-awareness, use of sensors, being executable on various mobile devices, limited hardware resources, etc. To this aim, in this... 

    Dual-diffusivity stochastic model for macromolecule release from a hydrogel

    , Article ACS Applied Bio Materials ; Volume 3, Issue 7 , 2020 , Pages 4208-4219 Jahanmir, G ; Lau, C. M. L ; Abdekhodaie, M. J ; Chau, Y ; Sharif University of Technology
    American Chemical Society  2020
    Abstract
    A three-dimensional model has been developed to describe the multiphase release of macromolecular drugs encapsulated in a hydrogel. The heterogeneity of network mesh size was considered by assigning varying diffusion coefficients to the network lattices randomly. Using a stochastic approach, the random nature of diffusion of drug molecules was captured within the network. The simplest form of distribution containing two diffusion coefficients was tested. To generate the drug release profiles for experimental validation under the limitation of computational cost, a simple scaling relationship was employed. Unlike the single-diffusivity model, the dual-diffusivity model showed good agreement... 

    A two-criteria objective function flexible flowshop scheduling problem with machine eligibility constraint

    , Article International Journal of Advanced Manufacturing Technology ; Volume 64, Issue 5-8 , April , 2013 , Pages 1001-1015 ; 02683768 (ISSN) Tadayon, B ; Salmasi, N ; Sharif University of Technology
    2013
    Abstract
    This research deals with a flexible flowshop scheduling problem with the arrival and delivery of jobs in groups and processing them individually. Each group of jobs has a specific release time. Due to the special characteristics of each job, only a specific group of machines in each stage are eligible to process that job. All jobs in a group should be delivered at the same time after processing. The objectives of the problem are the minimization of the sum of the completion time of groups on one hand and the minimization of sum of the differences between the completion time of jobs and the delivery time of the group containing that job (waiting period) on the other hand. The problem can be... 

    Modeling of transient permeate flux decline during crossflow microfiltration of non-alcoholic beer with consideration of particle size distribution

    , Article Journal of Membrane Science ; Volume 411-412 , September , 2012 , Pages 13-21 ; 03767388 (ISSN) Kazemi, M. A ; Soltanieh, M ; Yazdanshenas, M ; Sharif University of Technology
    2012
    Abstract
    Crossflow microfiltration of non-alcoholic beer is investigated numerically and it has been verified by experimental data. Due to the presence of particles with different sizes in feed suspension, a modified combination of three mechanisms of particle back-diffusion is developed to predict particle deposition and cake layer buildup during the process. The simulation results show that smaller particles (about 1μm) are the main contributor to the cake layer due to a minimum in back transport and are the main reason of the flux decline. On the other hand, larger particles (a p>20μm) are swept away along the membrane during the filtration process and move toward the membrane exit due to the... 

    Dynamic and static fracture analyses of graphene sheets and carbon nanotubes

    , Article Composite Structures ; Volume 94, Issue 8 , 2012 , Pages 2365-2372 ; 02638223 (ISSN) Niaki, S. A ; Mianroodi, J. R ; Sadeghi, M ; Naghdabadi, R ; Sharif University of Technology
    2012
    Abstract
    Dynamic and static fracture properties of Graphene Sheets (GSs) and Carbon nanotubes (CNTs) with different sizes are investigated based on an empirical inter-atomic potential function that can simulate nonlinear large deflections of nanostructures. Dynamic fracture of GSs and CNTs are studied based on wave propagation analysis in these nanostructures in a wide range of strain-rates. It is shown that wave propagation velocity is independent from strain-rate while dependent on the nanostructure size and approaches to 2.2×10 4m/s for long GSs. Also, fracture strain shows extensive changes versus strain-rate, which has not been reported before. Fracture stress is determined as 115GPa for GSs and... 

    Multi-product multi-chance-constraint stochastic inventory control problem with dynamic demand and partial back-ordering: A harmony search algorithm

    , Article Journal of Manufacturing Systems ; Volume 31, Issue 2 , 2012 , Pages 204-213 ; 02786125 (ISSN) Taleizadeh, A. A ; Niaki, S. T. A ; Seyedjavadi, S. M. H ; Sharif University of Technology
    Abstract
    In this paper, a multiproduct inventory control problem is considered in which the periods between two replenishments of the products are assumed independent random variables, and increasing and decreasing functions are assumed to model the dynamic demands of each product. Furthermore, the quantities of the orders are assumed integer-type, space and budget are constraints, the service-level is a chance-constraint, and that the partial back-ordering policy is taken into account for the shortages. The costs of the problem are holding, purchasing, and shortage. We show the model of this problem is an integer nonlinear programming type and to solve it, a harmony search approach is used. At the... 

    Structural stability of nano-sized crystals of HMX: A molecular dynamics simulation study

    , Article Applied Surface Science ; Volume 258, Issue 7 , 2012 , Pages 2226-2230 ; 01694332 (ISSN) Akkbarzade, H ; Parsafar, G. A ; Bayat, Y ; Sharif University of Technology
    Abstract
    The interaction potential energy and heat of sublimation of nanoparticles of HMX crystal polymorphs are studied by using molecular dynamics methods with a previously developed force field [Bedrov, et al., J. Comput.-Aided Mol. Des. 8 (2001) 77]. Molecular dynamics simulations of nanoparticles with 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 molecules of HMX are carried out at 300 K. The intermolecular, intramolecular and total interaction energies per mole for the nanoparticles are calculated at 300 K. Then, we have calculated sublimation enthalpy of HMX crystal polymorphs with different sizes. For the all sizes, the β-HMX is found to be the most stable phase, due to having the least total... 

    Protein corona composition of gold nanoparticles/nanorods affects amyloid beta fibrillation process

    , Article Nanoscale ; Volume 7, Issue 11 , Feb , 2015 , Pages 5004-5013 ; 20403364 (ISSN) Mirsadeghi, S ; Dinarvand, R ; Ghahremani, M. H ; Hormozi-Nezhad, M. R ; Mahmoudi, Z ; Hajipour, M. J ; Atyabi, F ; Ghavami, M ; Mahmoudi, M ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Abstract
    Protein fibrillation process (e.g., from amyloid beta (Aβ) and α-synuclein) is the main cause of several catastrophic neurodegenerative diseases such as Alzheimer's and Parkinson diseases. During the past few decades, nanoparticles (NPs) were recognized as one of the most promising tools for inhibiting the progress of the disease by controlling the fibrillation kinetic process; for instance, gold NPs have a strong capability to inhibit Aβ fibrillations. It is now well understood that a layer of biomolecules would cover the surface of NPs (so called "protein corona") upon the interaction of NPs with protein sources. Due to the fact that the biological species (e.g., cells and amyloidal... 

    A molecular dynamics study of fluid flows through slit-like nanochannels using two different driving systems

    , Article ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels Collocated with 3rd Joint US-European Fluids Engineering Summer Meeting, ICNMM2010, 1 August 2010 through 5 August 2010 ; Issue PARTS A AND B , 2010 , Pages 1029-1033 Darbandi, M ; Khaledi Alidusti, R ; Sabouri, M ; Abbasi, H. R ; Sharif University of Technology
    Abstract
    The Poiseuille flow through slit-like nanochannels is investigated using the nonequilibrium molecular dynamics simulations. To drive a dense flow through the channel, we use two self-adjusting vertical plates strategy. These plates force the liquid to flow through the nanochannel under adjustable inlet and outlet boundary conditions. Comparing with the dual-control-volume grand-canonical molecular dynamics method, the current strategy provides many advantages. The current strategy does not need particle insertion and deletion, therefore, the system dynamics would not be affected at all. Moreover, the number of particles in the simulation system is fixed due to inserting the two... 

    High power amplifier based on a transformer-type power combiner in CMOS technology

    , Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 57, Issue 11 , November , 2010 , Pages 838-842 ; 15497747 (ISSN) Javidan, J ; Atarodi, M ; Luong, H. C ; Sharif University of Technology
    2010
    Abstract
    In this brief, a transformer-type power combiner for a fully integrated high-power CMOS power amplifier (PA) is presented. The proposed power combiner is composed of a number of transformers that, unlike the ones in conventional approaches, have different sizes. This leads to higher efficiency and smaller chip area. After considering several power stage topologies, analysis and optimization of the transformer network (the power combiner) are presented. To demonstrate the advantages of the proposed architecture, a 900-MHz CMOS PA with the proposed power combiner was implemented with a 0.18-μm radio-frequency CMOS process. The amplifier achieved an efficiency value of 24% at the maximum output... 

    Optimal tension distribution and stiffness control of a spatial under-constrained cable suspended robot

    , Article Proceedings of the IASTED International Conference on Modelling, Identification and Control, 15 February 2010 through 17 February 2010 ; February , 2010 , Pages 270-275 ; 10258973 (ISSN) Hamedi, J ; Zohoor, H ; Sharif University of Technology
    2010
    Abstract
    In under-constrained spatial cable suspended robots, maximum number of cables are equivalent to the number of degree of freedom, therefore the equations of kinetostatic have unique solutions and invention of positive cable tensile forces in these robots must come into being by redundant cables, springs or by Moving Platform (MP) weight. In this research, MP weight is considered to create tension in cables so both increasing workspace volume and decreasing possibility of cable encounter with together can be created because of using less cables. The range of MP weight to generate tension in cables is calculated by using Interval method, optimum weight is selected and then optimal tension...