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Facile, scalable, and low-cost superhydrophobic coating for frictional drag reduction with anti-corrosion property
, Article Tribology International ; Volume 178 , 2023 ; 0301679X (ISSN) ; Rezaee, B ; Pakzad, H ; Moosavi, A ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Superhydrophobicity is a potential solution for corrosion inhibition and to mitigate increased fuel consumption. The facile, low-cost, and stable coating is developed in the present study. The contact angle of the coating is 160.1˚. In the pull-off test, the required force to detach the coating from the aluminum surface is about 7.55 MPa. The durability of the fabricated coating is tested under different environmental situations. The coating shows a drag reduction of roughly 40% compared to bare aluminum in the laminar flow regime due to the hierarchical micro-nano structure of the coated surface entrapping air pockets which alter the water boundary layer. © 2022 Elsevier Ltd
Superhydrophobic home-made polyurethane sponges for versatile and cost-effective oil and water separation
, Article Separation and Purification Technology ; Volume 276 , 2021 ; 13835866 (ISSN) ; Pakzad, H ; Fakhri, M ; Moosavi, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Utilizing 3D and 2D porous materials modified by a superhydrophobic/philic coating for quick removal of oil from water and a continuous process of oil/water separation, respectively, has attracted a lot of attention recently. Here we report the separation capacities of one commercial and three home-made sponges, sprayed by a superhydrophobic coating, for a broad range of oils and solvents. The contact angle of water on the coated sponges is 162.5˚, whereas the pristine sponge shows a contact angle of 91.8˚ (these values are for sponge D which had the highest absorption capacity). We investigate the effects of the density of sponges and the dynamic viscosity of oils and solvents on the...
The various versions of Bell's inequality: An alternative proof
, Article Journal of Physics A: Mathematical and General ; Volume 38, Issue 24 , 2005 , Pages 5565-5572 ; 03054470 (ISSN) ; Taqavi, M ; Sharif University of Technology
2005
Abstract
By considering uncommon factors as spacetime events that influence the spin orientations in the EPRB thought experiment, it is intended to show that one can still introduce the correlation functions. These uncommon factors are positioned inside the common lightcone of two particles. Then, Bell inequalities are proved with the preassumptions of local realism and spin conservation law in the context of a new scenario of hidden variables. © 2005 IOP Publishing Ltd
Design of Arch Dams with Axial and Biaxial Strength of Concrete Based on Permissible Safety Factor
, M.Sc. Thesis Sharif University of Technology ; Ghaemian, Mohsen (Supervisor)
Abstract
The dams as one of the most costly and most fundamental infrastructure that human steps to make their, always paid special attention to people in different historical periods. According to the high cost of this structure, optimum design is so important. On other hand stability of structure as main aspects of the design that in the absence of it is threatening the lives of many people in downstream. Therefor the engineers consider two important aspect when they want to design a dam. The first step in designing is determinate the external loads. A designer not only must recognize this loads but also by using the material that he consume in the body of dams reach to a safety structure in During...
Optimal apogee burn time for low thrust spinning satellite in low altitude
, Article European Journal of Operational Research ; Volume 222, Issue 2 , 2012 , Pages 386-391 ; 03772217 (ISSN) ; Assadian, N ; Sharif University of Technology
2012
Abstract
In this study, the optimal burn time for low-thrust impulsive propulsion systems is investigated to raise the perigee altitude of a low-Earth orbit. The maneuver is done using spin-stabilized attitude control and impulsive thrusting system for a time interval centered about apogee point. On the one hand, the low value of the thrust level causes more burn time needed to accomplish the transfer. This, in turn, will cause more thrust loss due to the deviation between the thrust axis (spin axis) and the velocity vector of the satellite. On the other hand, for small thrust duration, the transfer needs more revolutions around the Earth and more travel in lower altitudes with dense atmosphere and...
Operation of tapered steel slit dampers in steel structures using the endurance time method
, Article Civil-Comp Proceedings ; 2013 , Volume 102 ; 17593433 (ISSN) ; 9781905088577 (ISBN) ; Estekanchi, H.E ; Fakhri, M ; Sharif University of Technology
Civil-Comp Press
2013
Abstract
Based on special properties of metal dampers such as high energy dissipation, stable hysteric cycles, simple application, low cost, insensitivity to changes of temperature and the ability to substitute after the occurrence of earthquakes, they are being used for structural control. One of these metal dampers which has been of special interest is the tapered steel slit damper (TSS). When shear forces are applied, this damper yields and enters the plastic zone. The TSS damper is made of pieces of standard wide flanges where slits have been extracted from their web. These dampers are connected to the top of the chevron braces and under the middle of the beams. In the endurance time (ET) method...
Fabrication of Superhydrophobic Coating to Reduce Drag force with Anti-Corrosion and Anti-biofouling Properties
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor)
Abstract
Growth of the fuel consumption in the world and the greenhouse effect of its pollution get industrial managers and environmental activities attention. Skin drag force has a significant role in energy uses. The drag reduction property of superhydrophobic surfaces shows a new approach for investigators to reduce energy uses. Surface with 150° contact angle called superhydrophobic surface.In this project, a superhydrophobic coating is developed based on acrylic hydroxyl resin by silica nanoparticles. This coating can be sprayed on any surface. Using the Iron oxid particles and silica nanoparticles together produces hierarchical micro-nano structures. This coating has a 160.1° contact angle on...
Enhancement of dropwise condensation heat transfer through a sprayable superhydrophobic coating
, Article Langmuir ; Volume 39, Issue 23 , 2023 , Pages 8354-8366 ; 07437463 (ISSN) ; Mahlouji Taheri, M ; Pakzad, H ; Fakhri, M ; Moosavi, A ; Aryanpour, M ; Sharif University of Technology
American Chemical Society
2023
Abstract
Improving the shedding rate of condensed droplets has many applications in industries and daily problems, including increasing heat transfer and self-cleaning properties. One way to achieve this goal is by enhancement of the wetting properties of surfaces. In this research, the hierarchical superhydrophobic coating over aluminum has been applied using a relatively cost-effective method, spraying, which is also applicable to any metal surface used as a condenser. According to the results obtained from the experimental tests, the fabricated surface is highly superhydrophobic, with a contact angle of 158° and contact angle hysteresis of less than 5°. The results show that the presented surface...
A hybrid substrate for practical applications in dropwise condensation enhancement
, Article Applied Physics Letters ; Volume 123, Issue 5 , 2023 ; 00036951 (ISSN) ; Pakzad, H ; Mahlouji Taheri, M ; Talebi Chavan, R ; Fakhri, M ; Moosavi, A ; Aryanpour, M ; Sharif University of Technology
American Institute of Physics Inc
2023
Abstract
We introduce a durable hybrid substrate consisting of superhydrophilic micropillars surrounded by superhydrophobic depressions for practical industrial applications. The proposed surface can be mass-produced via a facile and affordable method. Moreover, the stability tests show that the wettability properties of fabricated surfaces do not vary after the imposition of hot steam flow for 110 h. Two hybrid samples with different patterns of micropillars are compared with superhydrophobic and bare aluminum samples to explore the physics behind the condensation improvement ability of hybrid surfaces. The results reveal that the heat transfer coefficient and heat flux can be significantly...
Bell inequalities and separability of uncommon causes from the setup configuration
, Article International Journal of Theoretical Physics ; Volume 45, Issue 11 , 2006 , Pages 2127-2135 ; 00207748 (ISSN) ; Seyed Yagoobi, S. K. A ; Taqavi, M ; Sharif University of Technology
2006
Abstract
In the present paper the integration region Λ with more than one hidden variable is attributed to a pair of particles in the Bell's thought experiment as the local causal events in their common lightcone. Moreover, the possibility of uncommon causal events influencing the spin measurement is not ignored. Then, with regard to the separability of the influence of the uncommon events from configuration of the setup, and by relying on local realism and coherency, each of the Bell's inequality versions is obtained by measuring spin in three and four different directions. © 2006 Springer Science+Business Media, Inc
Prevalence of smoking in 15-64 years old population of North of Iran: Meta-analysis of the results of non-communicable diseases risk factors surveillance system
, Article Acta Medica Iranica ; Volume 51, Issue 7 , 2013 , Pages 494-500 ; 00446025 (ISSN) ; Moosazadeh, M ; Masouleh, M. F ; Kiani, A ; Fakhri, M ; Sharif University of Technology
2013
Abstract
Smoking is known as a major cause of chronic obstructive pulmonary disease (COPD) and hence immediate and effective interventions are required for its elimination. This study aimed to collect valid data with regard to cigarette smoking in adult population of north of Iran for policy making by a meta-analysis of the documents of national non-communicable disease risk factors surveillance system. We investigated relevant evidences by searching in published and non-electronic databases. Data were extracted based on variables such as year of the study, sex, age group and prevalence of smoking habit. Based on results of heterogeneity, we applied fixed or random effects model to estimate the...
Highly efficient of molybdenum trioxide-cadmium titanate nanocomposites for ultraviolet light photocatalytic and antimicrobial application: Influence of reactive oxygen species
, Article Journal of Photochemistry and Photobiology B: Biology ; Volume 191 , 2019 , Pages 75-82 ; 10111344 (ISSN) ; Hosseini, M ; Fakhri, A ; Salari Rad, S ; Hadadi, T ; Nobakht, N ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In the present work we report the enhanced UV light photocatalytic performance of cadmium titanate photocatalyst by MoO 3 for Drug pollutant degradation. The nano photocatalyst sample was synthesized employing the Pechini-ultrasonic-hydrothermal route. Therefore, the nano photocatalyst were characterized by various analytical devices. The wide scan X-ray photoelectron spectral study confirmed the MoO 3 in the CdTiO 3 matrix. The crystallite size calculated with the Debye-Scherrer equation (55.4, 57.0, 61.2 and 63.1 nm for pure CdTiO 3 , MoCdTi-0, MoCdTi-1, and MoCdTi-2 nanocomposites, respectively). SEM micrographs revealed nanowire morphology indicated the crystalline nature of the sample....
Nonlinear interstory drift contours for idealized forward directivity pulses using "modified fish-bone" models
, Article Advances in Structural Engineering ; Volume 18, Issue 5 , May , 2015 , Pages 603-627 ; 13694332 (ISSN) ; Khosravi, H ; Jamnani, H. H ; Sharif University of Technology
Multi-Science Publishing Co. Ltd
2015
Abstract
Four 5-, 10-, 20- and 30-story moment frames, representing low-, mid-, and two high-rise structures, were subjected to a great number of idealized directivity pulses. The amplitudes and periods of pulses vary from 0.02 g to 1.0 g and 0.5 to 12 sec, respectively. Over 1400 nonlinear dynamic analyses of low- to high-rise moment frames were performed which were feasible through using modified fish-bone model. The distribution of interstory drift along the height was studied and two applied contours were proposed: (i) the maximum interstory drift contour, and (ii) the critical story contour. These contours were demonstrated versus the ratio of natural period of the structure to the pulse period...
Analysis of singularities of a 3DOF parallel manipulator based on a novel geometrical method
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Sadeghian, H ; Roozbehani, H ; Zohoor, H ; Sharif University of Technology
2006
Abstract
In this article singular points of a parallel manipulator are obtained based on a novel geometrical method. Here we introduce the constrained plain method (CPM) and some of its application in parallel mechanism. Given the definition of constraint plane (CP) and infinite constraint plane (ICP) the dependency conditions of constraints is achieved with the use of a new theorem based on the Ceva geometrical theorem. The direction of angular velocity of a body is achieved by having three ICPs with the use of another theorem. Finally, with the use of the above two novel theorems singularities of the 3UPF_PU mechanism are obtained. It should be emphasized that this method is completely geometrical,...
Melting enthalpy and entropy of freestanding metallic nanoparticles based on cohesive energy and average coordination number
, Article Journal of Physical Chemistry C ; Volume 115, Issue 35 , August , 2011 , Pages 17310-17313 ; 19327447 (ISSN) ; Delavari H., H ; Madaah Hosseini, H. R ; Sharif University of Technology
2011
Abstract
An analytical model is proposed to study the effect of particle size on melting enthalpy and entropy of metallic nanoparticles (NPs). The Mott's and Regel's equations for melting entropy in the combination of core average coordination number (CAC) and surface average coordination number (SAC) of freestanding NPs are considered. Clusters of icosahedral (IC), body centered cubic (BCC), and body centered tetragonal (BCT) structure without any vacancies and defects are modeled. Using the variable coordination number made this model to be in good agreement with experimental and molecular dynamic (MD) results of different crystal structures. The model predicts melting entropy and enthalpy of...
On the temperature and residual stress field during grinding
, Article WCE 2010 - World Congress on Engineering 2010, 30 June 2010 through 2 July 2010 ; Volume 2 , 2010 , Pages 1196-1200 ; 9789881821072 (ISBN) ; Farrahi, G. H ; Ghadbeigi, H ; Sharif University of Technology
2010
Abstract
Grinding is widely used for manufacturing of components that require fine surface finish and good dimensional accuracy. In this study a thermo-mechanical finite element analysis is conducted to find out how grinding parameters can affect temperature and residual stress distribution in the workpiece. Results of parametric study presented in this work indicate, by carefully selecting the grinding parameters, minimum thermal and mechanical damage can be achieved. Higher workpiece velocities produce higher surface residual stress. By increasing depths of cut, depth of tensile residual stresses increases. Convection heat coefficient does not have any considerable effect on surface residual stress...
A new lattic LP-based post filter for adaptive noise cancellers in mobile and vehicular applications
, Article Proceedings of the 8th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2008, 16 December 2008 through 19 December 2008, Sarajevo ; 2008 , Pages 407-412 ; 9781424435555 (ISBN) ; Sameti, H ; Veisi, H ; Abutalebi, H. R ; Sharif University of Technology
2008
Abstract
Adaptive Noise Cancellation (ANC) is a well-known technique for background noise reduction in automobile and vehicular environments. The noise fields in automobile and other vehicle interior obey the diffuse noise field model closely. On the other hand, the ANC does not provide sufficient noise reduction in the diffuse noise fields. In this paper, a new multistage post-filter is designed for ANC as a solution to diffuse noise conditions. The designed post-filter is a single channel Linear Prediction (LP) based speech enhancement system. The LP is performed by an adaptive lattice filter and attempts to extract speech components by using intermediate ANC signals. The post-filter has no...
Finite element analysis of shot-peening effect on fretting fatigue parameters
, Article Tribology International ; Volume 44, Issue 11 , 2011 , Pages 1583-1588 ; 0301679X (ISSN) ; Alvandi Tabrizi, Y ; Farrahi, G. H ; Majzoobi, G. H ; Ghadbeigi, H ; Sharif University of Technology
2011
Abstract
Shot peening is widely used to improve the fretting fatigue strength of critical surfaces. Fretting fatigue occurs in contacting parts that are subjected to fluctuating loads and sliding movements at the same time. This paper presents a sequential finite element simulation to investigate the shot peening effects on normal stress, shear stress, bulk stress and slip amplitude, which are considered to be the controlling parameters of fretting damage. The results demonstrated that among the modifications related to shot peening, compressive residual stress has a dominant effect on the fretting parameters
Mechanically activated synthesis of single crystalline MgO nanostructures
, Article Journal of Alloys and Compounds ; Volume 506, Issue 2 , September , 2010 , Pages 715-720 ; 09258388 (ISSN) ; Yoozbashizadeh, H ; Askari, M ; Kobatake, H ; Fukuyama, H ; Sharif University of Technology
2010
Abstract
One-dimensional (1D) MgO structures were successfully synthesized via carbothermic reduction of mechanically activated mixture of MgO and graphite. Mechanical activation of source materials before carbothermic reduction can substantially enhance the formation of MgO products at a temperature (1000 °C) relatively lower than that required in previous approaches (≥1200 °C). However, the morphology of MgO formed is dependent on the degree of mechanical activation and the condition of the subsequent carbothermic reduction. Two distinctive morphologies were found for MgO products synthesized using our method: single crystalline nanorods with rectangular cross-sections whose diameters range from 50...
Boundary control design for vibration suppression and attitude control of flexible satellites with multi-section appendages
, Article Acta Astronautica ; Volume 173 , 2020 , Pages 22-30 ; Salarieh, H ; Nejat Pishkenari, H ; Jalili, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Attitude and vibration control of a general form of flexible satellites is addressed in this paper. Partial differential dynamic equations are derived considering new details such as multi sectioned solar panels and elastic connections between main hub and solar panels. Boundary control approach is adopted to eliminate simplification errors of discrete models, using just one actuator in the hub. Asymptotic stability of attitude dynamics is proved for a group of boundary controllers and necessary conditions for asymptotic stability of vibrations are discussed. Being independent of modeling accuracy and using easily measurable feedbacks are among advantages of the proposed class of...