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Thermal analysis of various chromium compounds using TGA and DSC methods: a comparative investigation
, Article Journal of Thermal Analysis and Calorimetry ; Volume 149, Issue 17 , 2024 , Pages 9035-9043 ; 13886150 (ISSN) ; Khorablou, Z ; Nazari Alavi , A. R ; Sharif University of Technology
2024
Abstract
This study explored thermal behavior of four kinds of chromium compounds such as CrO3, K2Cr2O7, K2CrO4, and Cr2O3 using thermogravimetry (TG) and differential scanning calorimetry (DSC) method under the oxygen (O2) and nitrogen (N2) gas atmosphere at varying temperatures (25 to 1600 ℃). A diverse of chromium compounds were carefully evaluated for the first time through this method, and the present work provides new, comprehensive and valuable information regarding the mentioned compounds. XRD technique and elemental analysis were applied in order to recognize the products at diverse decomposition stages. The obtained products were then investigated via a SEM electron microscope. Also, the...
Surveying the jagorood river's self-purification
, Article 6th International Conference on Environmental Informatics, ISEIS 2007 ; 21-23 November , 2014 ; Mirzai, M ; Sajadi, S. A. A ; Alamolhoda, A. A ; Sharif University of Technology
2014
Abstract
the development and enlargement of city structure has caused the environmental problems on watershed of Latian dam which is one of the drinking water resourses of Tehran. The enlargement of Lavasan town and existence of an army garrison that it's effluents of treatment plant discharge to this river necessitate a water quality surveillance in entrance area of the dam. The present research includes the survey of this river's self-purification in the mentioned-above area. Numerical analysis is used in different methods to explain self- purification. Frist, we have the numerical analysis and analytical methods for a known sample in order to determine the accuracy and deviation between two...
Evaluation of Permeable Pavement in Removing Pollutants from Surface Runoff
, M.Sc. Thesis Sharif University of Technology ; Tajrishi, Masoud (Supervisor) ; Nazari Alavi, Alireza (Supervisor)
Abstract
Urbanization expansion increases impermeable surfaces and ultimately produces more runoff from urban surfaces. The runoff in the urban streets moves the pollution with high levels from the city and then collects into channels where they are transported into the water courses. The most important factor in runoff polluting is sediments. If you remove sediments from runoff, their quality will be improved. One of the effective systems to reduce sediments from the surface runoff is permeable pavement. In this study a simulator system is used. The sample of permeable pavement analysed consisted of two layers of geotextile beddig, filter granular layer (2.36 to 4.75mm), subbase granular layer (4.75...
Acceleration of Anaerobic Stabilization of Organic Solid Waste &Treatment of Following Sewage by a Biologic Tower
, M.Sc. Thesis Sharif University of Technology ; Hashemian, Jamaleddin (Supervisor) ; Nazari Alavi, Alireza (Supervisor)
Abstract
In this project, function of anaerobic digestion of organic waste in liquid phase and treating the following sewage in biologic tower(trickling filter) has been investigated in an experimental process. Solid waste were supplied from sharif university restaurant and after weighting and classification is added to tanks which filled by 40% sludge and 60% water. For controlling the function of biologic tower, a control reactor were used. Retention time for digestion of solid waste is 40 day. First solid loading was 500g and 75g organic waste in main & control reactor equal to 5(kg solid waste)/( m^3.reactor.day) 1.3(kg TS)/( m^3.reactor.day) and were doubled in second loading. It seems that...
Separation and Treatment of Cutting Oil Emulsions using Electrocoagulation
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor) ; Nazari Alavi, Alireza (Supervisor)
Abstract
Cutting oils are used for reducing friction, cooling and preventing from corrosion in the industry. These oils are mixed in different proportions with water and produce emulsion. In this study, treatment of oil-water emulsions is studied using electrocoagulation with aluminum, copper and stainless steel electrodes as a pretreatment stage. The efficiency of electrocoagulation process was obtained through the measurement of COD removal percentage and or the required time for the treatment. COD is the required oxygen for oxidizing oxidizable materials through oxidizing substances in the solution.In this study, the effect of operating parameters such as emulsion concentration (volume/volume...
Utilization of hydrogen in gas turbines: a comprehensive review
, Article International Journal of Low-Carbon Technologies ; Volume 17 , 2022 , Pages 513-519 ; 17481317 (ISSN) ; Fahim Alavi, M ; Salem, M ; Assad, M. E. H ; Sharif University of Technology
Oxford University Press
2022
Abstract
The concerns regarding the consumption of traditional fuels such as oil and coal have driven the proposals for several cleaner alternatives in recent years. Hydrogen energy is one of the most attractive alternatives for the currently used fossil fuels with several superiorities, such as zero-emission and high energy content. Hydrogen has numerous advantages compared to conventional fuels and, as such, has been employed in gas turbines (GTs) in recent years. The main benefit of using hydrogen in power generation with the GT is the considerably lower emission of greenhouse gases. The performance of the GTs using hydrogen as a fuel is influenced by several factors, including the performance of...
Drop formation from a capillary tube: comparison of different bulk fluid on newtonian drops and formation of newtonian and non-newtonian drops in air using image processing
, Article International Journal of Heat and Mass Transfer ; Volume 124 , 2018 , Pages 912-919 ; 00179310 (ISSN) ; Zadkazemi Derakhshi, A ; Nazari, A ; Firoozabadi, B ; Sharif University of Technology
2018
Abstract
The formation of water drops as a Newtonian fluid and formation of a shear-thinning non-Newtonian fluid, Carboxyl Methyl Cellulose (CMC) from a capillary into different bulk fluids are experimentally investigated. A high speed camera is used to visualize the images of the drops and an image-processing code employed to determine the drop properties from each image. It was found that the properties of the water drops when they are drooped into the liquids bulk fluids such as toluene and n-hexane are almost the same while they differed substantially when they were drooped into the air bulk fluid. It is shown that during the formation of water drop in all three kinds of bulk fluids, the drop...
Application and evaluation of RUSLE erosion model in JAJROOD watershed (ROODAK) with G.I.S
, Article Proceedings of the 2nd IASTED International Conference on Environmental Management and Engineering, EME 2010, 15 July 2010 through 17 July 2010, Banff, AB ; July , 2010 , Pages 879-887 ; 9780889868526 (ISBN) ; Sajadi, A ; Nazari, A ; Sharif University of Technology
2010
Abstract
In this study amount of soil erosion in watershed of JAJROOD is estimated by use of the RULSE model with the help of GIS12. JAJROOD River is located in upstream of LATIAN Dam and is one of the most important water sources of Tehran. Also, this River has a big role in preventing the flood. modeling Results show that the amount of soil erosion is high due to high slope of the land, lack of plant coverage and the quality of soil and changing the land application, lead to increase in erosion potential. modeling Results have estimated the amount of erosion in this basin about 1,524,511 tons in a year. In order to evaluate Results and efficiency of the model, all of obtained results are compared...
Human interaction with IoT-based smart environments
, Article Multimedia Tools and Applications ; 2016 , Pages 1-23 ; 13807501 (ISSN) ; Semsar, A ; Sharif University of Technology
Springer New York LLC
2016
Abstract
This paper describes concepts, design, implementation, and performance evaluation of a 3D-based user interface for accessing IoT-based Smart Environments (IoT-SE). The generic interaction model of the described work addresses some major challenges of Human-IoT-SE-Interaction such as cognitive overload associated with manual device selection in complex IoT-SE, loss of user control, missing system image or over-automation. To address these challenges we propose a 3D-based mobile interface for mixed-initiative interaction in IoT-SE. The 3D visualization and 3D UI, acting as the central feature of the system, create a logical link between physical devices and their virtual representation on the...
Human interaction with IoT-based smart environments
, Article Multimedia Tools and Applications ; Volume 76, Issue 11 , 2017 , Pages 13343-13365 ; 13807501 (ISSN) ; Semsar, A ; Sharif University of Technology
Springer New York LLC
2017
Abstract
This paper describes concepts, design, implementation, and performance evaluation of a 3D-based user interface for accessing IoT-based Smart Environments (IoT-SE). The generic interaction model of the described work addresses some major challenges of Human-IoT-SE-Interaction such as cognitive overload associated with manual device selection in complex IoT-SE, loss of user control, missing system image or over-automation. To address these challenges we propose a 3D-based mobile interface for mixed-initiative interaction in IoT-SE. The 3D visualization and 3D UI, acting as the central feature of the system, create a logical link between physical devices and their virtual representation on the...
Concurrent design of Schottky diode limiter and LNA
, Article Analog Integrated Circuits and Signal Processing ; Volume 107, Issue 3 , 2021 , Pages 543-550 ; 09251030 (ISSN) ; Medi, A ; Sharif University of Technology
Springer
2021
Abstract
In this paper concurrent design of Schottky diode based limiter and low noise amplifier (LNA), based on noise matching, is investigated to achieve minimum noise figure (NF) of the receiver chain. In design procedure of the LNA, the noise figure is minimum, gain at central frequency is 14.5 dB, and limiter structure tolerates up to 5 W continuous wave input power. In the proposed concurrent design, a pass-band filter is applied at the LNA output to attenuate undesired out-of-band signals. In the proposed design, the limiter-LNA is implemented with a 0.25 µm gate length AlGaAs/InGaAs pHEMT process. Measured noise figure of chain is 2.7 dB and average gain over 8.5–9.5 GHz frequency range and...
Concurrent design of Schottky diode limiter and LNA
, Article Analog Integrated Circuits and Signal Processing ; Volume 107, Issue 3 , 2021 , Pages 543-550 ; 09251030 (ISSN) ; Medi, A ; Sharif University of Technology
Springer
2021
Abstract
In this paper concurrent design of Schottky diode based limiter and low noise amplifier (LNA), based on noise matching, is investigated to achieve minimum noise figure (NF) of the receiver chain. In design procedure of the LNA, the noise figure is minimum, gain at central frequency is 14.5 dB, and limiter structure tolerates up to 5 W continuous wave input power. In the proposed concurrent design, a pass-band filter is applied at the LNA output to attenuate undesired out-of-band signals. In the proposed design, the limiter-LNA is implemented with a 0.25 µm gate length AlGaAs/InGaAs pHEMT process. Measured noise figure of chain is 2.7 dB and average gain over 8.5–9.5 GHz frequency range and...
On control of spacecraft relative motion in the case of an elliptic keplerian chief
, Article Advances in the Astronautical Sciences ; Vol. 150, issue , August , 2014 , p. 1413-1432 ; 2195268X ; Butcher, E. A ; Mesbahi, A ; Sharif University of Technology
2014
Abstract
In this study, control strategies based on time-varying LQR, Lyapunov-Floquet transformation (LFT), backstepping, feedback linearization, and constant gain feedback control are implemented for the linearized time periodic equations of spacecraft relative motion when the reference orbit is elliptic. Also, natural and nonnatural leader-follower two-spacecraft formations are studied. The stability of the closed-loop response, the control effort required, and the settling time are investigated and compared for all control strategies. Furthermore, using constant gain feedback, the estimated region of attraction of the closed-loop system is obtained analytically
Strength assessment and bonding study of aluminum short fiber-reinforced gypsum composites
, Article International Journal of Damage Mechanics ; Volume 21, Issue 1 , January , 2012 , Pages 129-149 ; 10567895 (ISSN) ; Sangghaleh, A ; Nazari, A ; Sharif University of Technology
2012
Abstract
In this study, tensile strength of gypsum-based composite with aluminum fibers up to 15 vol.% was studied. To increase the interfacial bond strength between fibers and matrix, aluminum fibers were anodized under different conditions. Single fiber pull-out tests were carried out to investigate the bond strength. The interface was examined by scanning electron microscope. The ability of the composites to withstand longitudinal tensile load was also studied by tensile tests of dog bone-shaped, randomly oriented fiber-reinforced gypsum. By the introduction of aluminum fibers in gypsum as a randomly oriented composite, considerable increment in the strength is achieved and the toughness of the...
On the minimization of the exit profile curvature in extrusion through multi-hole dies: a methodology and some verifications
, Article Meccanica ; Volume 50, Issue 5 , May , 2015 , Pages 1249-1261 ; 00256455 (ISSN) ; Assempour, A ; Sharif University of Technology
Kluwer Academic Publishers
2015
Abstract
In this study, a methodology has been presented for radial positioning of the die holes in multi-hole extrusion of non-symmetric sections. The objective of radial positioning is to minimize exit profile curvature. For this purpose, a two-hole die with non-symmetric T-shaped holes has been investigated. A kinematically admissible velocity field at deformation zone has been developed. The deformation region includes the dead metal zone (DMZ) which is assumed to be linear. The DMZ length was obtained by energy minimization through the upper bound method. To predict the exit profile curvature a deviation function has been suggested. Using the proposed function, the velocity field has been used...
Anaerobic treatment by UASB reactor and aerobic biodegradability test of cutting oil sewage
, Article Journal of Environmental Studies ; Vol. 40, issue. 1 , 2014 , p. 211-220 ; Sajadi, A. A ; Mirzaei, M ; Hoseynian, H ; Sharif University of Technology
2014
Abstract
Introduction: Water is consumed in almost all industries. Consequently the used water is turning to a waste that usually should be treated to meet the regulated standard level prior to reuse or discharge into the environment. Cutting oil wastewater is an emulsion normally comprised ofl-10% oil and the remainder water. The main functions of this oil in industry are lubrication, friction reduction, and cooling of instrument s parts. This wastewater is classified as a toxic waste according to the existence of some additive material to prevent corrosion and bacterial growth. Breakage of the emulsion and separation of the water and the oil can alone reduce more than about 90% of the aqueous phase...
Vectorial Gaussian beam tracing method for millimeter wave propagation modelling in a large scale media
, Article 2009 Mediterrannean Microwave Symposium, 15 November 2009 through 17 November 2009 ; 2009 ; 9781424446643 (ISBN) ; Naqavi, A ; Shabani, M ; Shishegar, A. A ; Sharif University of Technology
2009
Abstract
We use the 3D vectorial Gaussian beam tracing method to model millimeter wave propagation. We simulate the propagation of Gaussian beams in a large scale environment at 62.4 GHz. First, a known far field pattern of the transmitter antenna is expanded into a set of Gaussian beams. We chose Gabor expansion based method to expanding radiating field into Gaussian beams. Then, a Gaussian beam tracing model considering reflections and transmission is used to represent urban microcell propagation. We use a phase matching method to find reflected Gaussian beam The results of the Gaussian beam tracing simulations including line-of-sight (LOS) and non-Iine-of-sight (NLOS) propagation are compared with...
Pool boiling heat transfer in dilute water/triethyleneglycol solutions
, Article Chinese Journal of Chemical Engineering ; Volume 17, Issue 4 , 2009 , Pages 552-561 ; 10049541 (ISSN) ; Safekordi, A. A ; Jamialahmadi, M ; Sharif University of Technology
2009
Abstract
Boiling of water/triethyleneglycol (TEG) binary solution has a wide-ranging application in the gas processing engineering. Design, operation and optimization of the involved boilers require accurate prediction of boiling heat transfer coefficient between surface and solution. In this investigation, nucleate pool boiling heat transfer coefficient has been experimentally measured on a horizontal rod heater in water/TEG binary solutions in a wide range of concentrations and heat fluxes under ambient condition. The present experimental data are correlated using major existing correlations. In addition a correlation is presented for prediction of pool boiling heat transfer for the system in which...
Investigation of thermal behavior of α-PbO and β-PbO IN O2 atmosphere
, Article Metalurgija ; Volume 57, Issue 4 , 2018 , Pages 287-290 ; 05435846 (ISSN) ; Nazari Alavi, A ; Mirzai, M ; Sharif University of Technology
Faculty of Metallurgy
2018
Abstract
The compounds α-lead oxide (α-PbO) and β-lead oxide (β-PbO) were purchased from Merck co. and used for thermal investigations in laboratory. The compound was heated in a thermogravimeter at different temperature, from 25 to 400 °C. The used gas atmosphere was O2. The received products were investigated by X-ray diffraction (XRD) technique. The received product Pb3O4 was confirmed by XRD. The textures of two different morphologies of α-PbO, β-PbO and the product Pb3O4 is investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. © 2018, Faculty of Metallurgy. All rights reserved
Experimental investigation in pool boiling heat transfer of pure/binary mixtures and heat transfer correlations
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 27, Issue 3 , September and October , 2008 , Pages 135-150 ; 10219986 (ISSN) ; Jamialahmadi, M ; Safekordi, A. A ; Sharif University of Technology
2008
Abstract
Nucleate pool boiling heat transfer coefficient have been experimentally measured on a horizontal rod heater for various liquid binary mixtures. Measurements are based on more than three hundred data points on a wide range of concentrations and heat fluxes. In this investigation, it has been confirmed that the heat transfer coefficient in boiling solutions are regularly less than those in pure component liquids with same physical properties. Several reasons should be responsible for this phenomenon, but mainly it could be related to preferential evaporation of the more volatile component(s) during bubble formation. In this article, the performances of major existing correlations to the...