Loading...
Search for:
ashrafi--abolfazl
0.151 seconds
Total 159 records
Droplet condensation on chemically homogeneous and heterogeneous surfaces
, Article Journal of Applied Physics ; Volume 120, Issue 12 , 2016 ; 00218979 (ISSN) ; Moosavi, A ; Sharif University of Technology
American Institute of Physics Inc
2016
Abstract
Nucleation and growth of condensing droplets on horizontal surfaces are investigated via a 2-D double distribution function thermal lattice Boltzmann method. First, condensation on completely uniform surface is investigated and different mechanisms which cause dropwise and filmwise condensation are studied. The results reveal the presence of cooled vapor layer instability in the condensation on completely smooth surfaces. In the second step, condensation on chemically heterogeneous surfaces is investigated. Moreover, the effect of non-uniformity in the surface temperature is also studied. The results indicate that the vapor layer instability and the nucleation start from the heterogeneities....
Biomass Separation in Moving Bed Biofilm Reactors (MBBR) by Natural And Innovative Filters
, M.Sc. Thesis Sharif University of Technology ; Borgheei, Mahdi (Supervisor)
Abstract
The application of membranes for separate of particles in mainly microbial flacs , are fast growing in biological treatment systems. Membrane bioreactors are now considered as one of the major new processes in wastewater treatment. However , membranes are expensive and costly. This study is carried out to test an innovative , locally made filters for separation of flocs in an MBBR reactor. This innovative filter is replacing a traditional settling tank. This type of filters is made very cheaply and has important advantages in installing and operation. Experiments were carried out in a laboratory scale MBBR unit. A filter unit consisting of 3 innovative filter tubes were placed and the...
Continuous-thrust Trajectory Optimization in the Binary Asteroids System
, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima (Supervisor)
Abstract
In this thesis, the optimal trajectories of a spacecraft in the binary asteroids system is studied. The objective functions of optimal trajectories in these system are the maximum coverage of the asteroids surface and minimum time and fuel consumption. For this purpose, the dynamic of binary system is modeled. The binary system of 1999 KW4 is selected as a case study. The ellipsoid-sphere model is a good approximation for the case of this study. In this model, the asteroids orbit in a circular orbit around each other in a spin-spin-orbit resonance configuration, in which the asteroids’ rotational velocity is equal to orbital mean motion. Then, the equations of motion of the spacecraft as the...
New correlation for calculating natural gas Z-factor
, Article Hydrocarbon Processing ; Volume 89, Issue 10 , 2010 ; 00188190 (ISSN) ; Ghotbi, C ; Sharif University of Technology
2010
Droplet condensation and jumping on structured superhydrophobic surfaces
, Article International Journal of Heat and Mass Transfer ; Volume 134 , 2019 , Pages 680-693 ; 00179310 (ISSN) ; Moosavi, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A complete cycle of droplet nucleation, growth, coalescence and jumping on different textured hydrophobic and superhydrophobic surfaces is studied for the first time, using a 2-D double distribution function thermal lattice Boltzmann method. First, droplet nucleation mechanism on smooth and rough surfaces is studied in detail. The results reveal the presence of cooled vapor layer instability in the condensation on completely smooth surfaces. However, on the rough surfaces and near the roughness a completely different mechanism is observed and the nucleation occurs on the roughness wedges. Also, the condensation on different textured surfaces with nominal contact angles θa=90°,120°,155° is...
An Investigation on the Behavior of Bolted Connections using Friction Drilling in Shear and Tension
, M.Sc. Thesis Sharif University of Technology ; Ahmadizadeh, Mehdi (Supervisor)
Abstract
Friction drilling or flow drilling is a method of making holes in metal sheets, in which the material is pushed with the aid of heat from friction. This procedure allows making holes in sheet metal, with a sleeve formed as the hole is created. This sleeve is then threaded and used as the nut, thus eliminating the need for access to the interior faces of hollow steel sections. On the other hand, with the development of advanced manufacturing techniques, larger and thicker hollow structural sections are becoming more popular in mid-rise and multistory structures. onsequently, flow drilling can be considered as a viable alternative for traditional drilling techniques, where the material is...
A novel management scheme to reduce emission produced by power plants and plug-in hybrid electric vehicles in a smart microgrid
, Article International Journal of Environmental Science and Technology ; Volume 17, Issue 5 , 2020 , Pages 2529-2544 ; Soleymani, S ; Mehdi, E ; Sharif University of Technology
Springer
2020
Abstract
Recently, with the growth and development of distributed generation (DGs) and energy storage systems (ESSs), as well as smart control equipment, microgrids (MGs) have been developed. Microgrids are comprised of a limited number of constitutive parts, including loads, DGs, ESSs, and electric vehicles (EVs). This paper presents a novel scheme to manage active and reactive powers, based on DGs, ESSs, and EVs to reduce the total operation cost including power generation and emission costs. Simultaneous management of active and reactive power makes it possible to consider grid operation constraints together. In the proposed schedule, the vehicles are assumed to be plug-in hybrid electric...
Recycling of Cobalt with the form of Cobalt Nano Oxide from Spent Li-ion Batteries
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
One of the most important methods for recycling of spent Li-ion batteries is acid leaching that various parameters affect it. In this work, influences of effective parameters on the percent of cobalt and lithium recovery with application of design of experiments (response surface methodology-central composite) were investigated and then cobalt nano oxide as the by-product synthesized by pulsing lectrolysis. In the first Phase, effects of parameters such as sulfuric acid oncentration: 2-6 molar, hydrogen peroxide volume percent: 5-10%, S/L ratio: 20-50 g/L and temperature: 50-80°C on cobalt and lithium recovery were investigated and finally an adequate model presented. For all experiments,...
Numerical Study of Geotextile Application in Downstream Filter Zone of an Embankment Dam with Clay Core
, M.Sc. Thesis Sharif University of Technology ; Shamsaie, Abolfazl (Supervisor)
Abstract
Nowadays, applications of the synthetic materials are developing in civil engineering projects and widely used in these projects. Therefore, during previous years; use of the Geotextiles as one of the Geosynthetic materials in order to filtration, drainage, separation, soil protection, etc have developed ever-increasing. The goal of this research is modeling and studies of the Geotextiles application in the downstream filter zone of embankment dams in combination with granular materials using FLAC2D software. Gordeh Bin embankment dam situated in West Azerbaijan province has been chosen as case study. In this matter, different models have been made with changes in thickness of the inclined...
groundwater level fluctuations forecasting using conjunction models of Wavelet - Neural-Fuzzy Network (WNF) and Wavelet-Neural Network (WNN) and linear model of ARIMA (case study: Qom plain
,
M.Sc. Thesis
Sharif University of Technology
;
Shamsaei, Abolfazl
(Supervisor)
Abstract
Prediction of groundwater level fluctuations is absolutely necessary for the proper manag ement of these precious resources. There are different methods to predict hydrological time series such as groundwater level. Linear models inefficiency in predicting nonlinear and n on-stationary time series cause researchers widely use artificial intelligence techniques such as Artificial Neural Networks (ANN), Fuzzy Inference System (FIS), Genetic Algorithm (GA) and their hybrid models such as Artificial Neural – Fuzzy Inference System (ANFIS). These smart models are capable to simulate nonlinear and non-stationary time series in suitable accu-racy using by a few time and data. By emersion of Wavelet...
, M.Sc. Thesis Sharif University of Technology ; Shamsaei, Abolfazl (Supervisor)
Abstract
Entrance of air to close water conduits occurs in many ways. This phenomenon makes displeasing effects on water transport structures. Two-phase flows in closed conduits are studied experimentally, numerically and theoretically. Even after decades, due to the complexity of the subject, these studies still require development and reformation. Numerical and theoretical two-phase models are often limited to a special regime of flow."Volume Of Fluid"(VOF) is a model for non-mixing two-phase flows. "Fluent" software uses this model in this field of flows. Volume of fluid is used successfully in some problems like dam break or rising bubbles. Main disadvantage of this model is distribution of the...
Assessment of waterlogging and provide risk maps by using RS, GIS and field data (case study: Qazvin plain)
,
M.Sc. Thesis
Sharif University of Technology
;
Shamsaei, Abolfazl
(Supervisor)
Abstract
Groundwater quality protection has a significant importance due to abundant applications of these resources in various fields such as agriculture, industry and drinking water. Removal of groundwater pollution is a time and money consuming process and often pollution is detected when improving the quality of groundwater is nearly impossible. For this vulnerability assessment there are three methods: Processing, Overlap-Index and Statistical Methods. Overlap-Index is composed of variety of maps such as Geology, Soil, Groundwater Depth and etc which uses in determining of vulnerability Index. In the present study for underground pollution potential determining, four indexes such as AVI، GOD،...
Efficient Management of River Water Quality Based on Pollution Trading Approach
, Ph.D. Dissertation Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
“Sustainable development” is a frequently used phrase, but the idiom has been experienced little since it was coined by the Brundtland, due to its intrinsic complications. The issue is going to compromise two key components; economy and ecology. One of the solutions based on concept of sustainable development that has been proposed for maintaining water quality at acceptable levels is to cap pollutant emissions at a sustainable level, then establish an economic market in which the right to discharge pollutants is traded according to market supply and demand mechanisms. Water quality trading or pollution trading is one such kind of market-based program that has also been described using names...
Semi-supervised Breast Cancer Subtype Clustering Using Microarray Datasets
, M.Sc. Thesis Sharif University of Technology ; Motahhari, Abolfazl (Supervisor)
Abstract
Gene expression microarrays can be used for precision medicine and targeted therapies. The data generated by microarrays are high-dimensional causing statistical inference of any parameter a daunting task. In this thesis, it is shown that regardless of high-dimensional datasets produced by microarrays, the inference can be robust in the sense that random selection of features results in the same conclusion as far as the number of selected features are chosen appropriately. Stratifying patients with breast cancer based on their gene expression levels shows that patient subtypes are almost independent of the feature selection strategy. Moreover, using less noisy datasets coming from RNAseq...
A Simulation for Better Understanding of Integrin Clustering and Activation
, M.Sc. Thesis Sharif University of Technology ; Motahhari, Abolfazl (Supervisor)
Abstract
Today, computer simulations are employed prevalently by researchers to understand biological processes. The tendency to use computational methods has been increased recently due to the high costs and errors of experimental methods. Integrins are membrane proteins that mechanically attach cells to the extra cellular matrix (ECM) and derive some behaviors such as cell migration. Moreover, integrins have biochemical functions. They transduce environment signals and trigger chemical pathways. As a result, integrins regulate cell shape, motility, etc. The investigation of integrin behavior in a real environment is very difficult due to the presence of many other proteins that interfere with the...
Hydro-economical Method for the Optimal Capacity Design of Small Hydropower Plant (Case Study: Kohneh Lahijan Hydropower Plant)
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
In this thesis, we determine the optimal capacity of the power plants considering site specifications and Flow Duration Curve and evaluating economic parameters. Finally a design with more sufficient economical and hydrualical performance would be selected. The optimization algorithm used in this thesis is called "Charged System search" that is one of the newest meta-heuristic algorithms. This algorithm is inspired by the coulomb and gauss's laws of electrostatics in physics and utilizes a number of charged particles which influence each other based on their fitness values and their separation distances considering the governing law of coulomb.The proposed method in this thesis can be...
GIS Based Procedure to Determine Location of Cascade Small Hydropower Plants Case Study, Nokhan Area
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
Coinciding with the worldwide environmental issues and increasing demand for clean energy sources, hydropower plants have highly attracted decision- makers attention. Low manufacturing costs and pollutions which are made by these plants in comparison with another types of powerhouses, could be reason of that. And so on, hydropower locating and evaluating studies have been highly increased recently, specifically in developing countries. From the point of operation procedure, hydropower plants are generally divided in two types, run-of-he-river and storage projects. This study has concentrated on run-of-he-river projects and due to spotting plant location, Sefidbarg river basin...
Investigation of bed Stability in Downstream for the Diversion dam under Scour (Mill & Moghan case study)
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
Numerical simulations and large eddy simulations (LES) of turbulent flow downstream of diversion dam , pool-riffle bedform in different geometrical ratios (different lengths of riffle and pool) with flow Reynolds number of 3.0 E+04 to 3.3E+04, downstream of special case study "Mill and Moghan diversion dam" with Froude number of 0.5 are presented The calculations are performed using a computational fluid dynamics model, FLOW-3D, which solves the Navier-Stokes equations in three dimensions with finite volume method. Numerical simulations are validated by comparing the numerical results of time-averaged flow patterns downstream of pool-riffle sequence with that of the experimental...
Assessment of Optimum Environmental Flows Using Economic Evaluation Methods
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
One of the main challenges of Water Resources Planning and Management (WRPM) is to balance water allocation between different uses. Usually, due to political and economic power of other uses, ecosystem receives less attention. Environmental flow is the allocated flow to ecosystem. Ecosystem provides a wide range of services to humanity. Therefore, environmental flow is not exclusively a matter of sustaining ecosystem but also a matter of providing humans with better life. Several methods have been developed to determine the environmental flow but only a few consider its socio-economic aspects. Consideration of these aspects could assist decision-makers with determining the optimum flow and...
Application of Gis & Fuzzy Technique for Order-Preference by Similarity to Ideal Solution (Topsis) in Siting Water Reservoires
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
Sustainable agricultural development in the country without regard to water supply problems in terms of time and place is not possible. Construction of water storage tanks filled with water and seasonal use in dry seasons in the effective action in the optimal use of water in the climate of (low and irregular rainfall) is. The most important step in the construction of water storage tanks to choose the best point for the construction of the reservoir basin in order to reduce costs and increase efficiency. Chndmyarh different methods to decide the best option for finding a few options from there. Among these methods can be Tapsys two methods (TOPSIS) and hierarchical analysis (AHP) pointed...