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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...
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
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...
A simulation optimization approach to un-paced assembly line balancing problem-II with additional reworking issue
, Article 2011 4th International Conference on Modeling, Simulation and Applied Optimization, ICMSAO 2011, 19 April 2011 through 21 April 2011 ; April , 2011 , Page(s): 1 - 6 ; 9781457700057 (ISBN) ; Bahalke, U ; Dolatkhahi, K ; Yolmeh, A. M ; Sharif University of Technology
2011
Abstract
This paper investigates the problem of assembly line balancing problem, in which the products in the production line may undergo to be reworked on the current task. Since the real manufacturing systems deal with the stochastic nature of the items in production lines, this paper considers the simple assembly line balancing problem type 2 (SALBP-II) under the conditions of stochastic processing time of tasks and the element of reworking system. Exposing to the stochastic conditions encouraged us to handle the problem via simulation optimization procedure, which uses the well known genetic algorithm as an optimization tool. Results show the adaptation and effectiveness of GA to considered...
Solvent-free three-component condensation reaction of aromatic ketones with aliphatic amines and formaldehyde
, Article Journal of Chemical Research - Part S ; Issue 8 , 2000 , Pages 380-381 ; 03082342 (ISSN) ; Saidi, M. R ; Sharifi, A ; Noushabadi, M ; Bolourtchian, M ; Sharif University of Technology
Scientific Reviews Ltd
2000
Abstract
A solvent-free procedure for the synthesis of several 1-aryl-2-(dialkylaminomethyl)-prop-2-en-1-ones 3 (a-e) and 4 (a-e) is reported. Reaction of arylmethyl ketones with formaldehyde and dialkylamines, such as diethyl- or dibutylamines at room temperature in silica gel produce 3 and 4 with moderate yields
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...
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...
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...
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
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 neuro-optimal approach for thrust-insensitive trajectory planning
, Article Aircraft Engineering and Aerospace Technology ; Volume 81, Issue 3 , 2009 , Pages 212-220 ; 00022667 (ISSN) ; Pazooki, F ; Noushabadi, F ; Sharif University of Technology
2009
Abstract
Purpose - The purpose of this paper is to devise a new approach to synthesize closed-loop feedback guidance law for online thrust- insensitive optimal trajectory generation utilizing neural networks. Design/methodology/approach - The proposed methodology utilizes an open- loop variational formulation that initially determines optimal launch/ ascent trajectories for various scenarios of known uncertainties in the thrust profile of typical solid propellant engines. These open-loop optimized trajectories will then provide the knowledge base needed for the subsequent training of a neural network. The trained network could eventually produce thrust-insensitive closed-loop optimal guidance laws...
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...
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...
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
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....
Estimation of higher heating values (HHVs) of biomass fuels based on ultimate analysis using machine learning techniques and improved equation
, Article Renewable Energy ; Volume 179 , 2021 , Pages 550-562 ; 09601481 (ISSN) ; Dashti, A ; Ahmadijokani, F ; Hu, J ; Mohammadi, A. H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
To have a sustainable economy and environment, several countries have widely inclined to the utilization of non-fossil fuels like biomass fuels to produce heat and electricity. The advantage of employing biomass for combustion is emerging as a potential renewable energy, which is regarded as a cheap fuel. Chemical constituents or elements are essential properties in biomass applications, which would be costly and labor-intensive to experimentally estimate them. One of the criteria to evaluate the energy of biomass from an economic perspective is the higher heating value (HHV). In the present work, we have applied multilayer perceptron artificial neural network (MLP-ANN), least-squares...
Probability of missed detection as a criterion for receiver placement in MIMO PCL
, Article IEEE National Radar Conference - Proceedings, 7 May 2012 through 11 May 2012, Atlanta, GA ; 2012 , Pages 0924-0927 ; 10975659 (ISSN) ; 9781467306584 (ISBN) ; Chitgarha, M. M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
IEEE
2012
Abstract
Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar
An efficient method for the ring opening of epoxides with aromatic amines by Sb(III) chloride under microwave irradiation
, Article Journal of Chemical Research ; Issue 4 , 2008 , Pages 220-221 ; 03082342 (ISSN) ; Hashemi, M. M ; Mottaghi, M. M ; Foroughi, M. M ; Sharif University of Technology
2008
Abstract
SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity
Resource allocation for uav-enabled integrated sensing and communication (isac) via multi-objective optimization
, Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; Volume 2023-June , 2023 ; 15206149 (ISSN); 978-172816327-7 (ISBN) ; Naghsh, M. M ; Karbasi, M ; Nayebi, M. M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
In this paper, we consider an integrated sensing and communication (ISAC) system with wireless power transfer (WPT) where an unmanned aerial vehicle (UAV)-based radar serves a group of energy-limited communication users in addition to its sensing functionality. In this architecture, the radar senses the environment in phase 1 (namely sensing phase) and mean-while, the communications users (nodes) harvest and store the energy from the radar transmit signal. The stored energy is then used for information transmission from the nodes to UAV in phase 2, i.e., uplink phase. Performance of the radar system depends on the transmit signal as well as the receive filter; the energy of the transmit...
MIMO radar signal design to improve the MIMO ambiguity function via maximizing its peak
, Article Signal Processing ; Volume 118 , 2016 , Pages 139-152 ; 01651684 (ISSN) ; Radmard, M ; Nazari Majd, M ; Karbasi, S. M ; Nayebi, M. M ; Sharif University of Technology
Elsevier
2016
Abstract
One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function...