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Natural convection from a confined horizontal cylinder: The optimum distance between the confining walls
, Article International Journal of Heat and Mass Transfer ; Volume 44, Issue 2 , 2001 , Pages 367-374 ; 00179310 (ISSN) ; Razi, Y. P ; Sharif University of Technology
2001
Abstract
The laminar natural convection from an isothermal horizontal cylinder confined between vertical walls, at low Rayleigh numbers, is investigated by theoretical, experimental and numerical methods. The height of the walls is kept constant, however, their distance is changed to study its effect on the rate of the heat transfer. Results are incorporated into a single equation which gives the Nusselt number as a function of the ratio of the wall distance to cylinder diameter, t/D, and the Rayleigh number. There is an optimum distance between the walls for which heat transfer is maximum. © 2000 Elsevier Science Ltd. All rights reserved
Efffects of confining walls on laminar natural convection from a horizontal cylinder
, Article 35th Intersociety Energy Conversion Engineering Conference and Exhibit 2000, Las Vegas, NV, 24 July 2000 through 28 July 2000 ; 2000 ; Pedram Razi, Y ; Sharif University of Technology
2000
Abstract
The laminar natural convection from an isothermal horizontal cylinder confined between vertical walls is investigated by experimental and numerical methods. The experimental and numerical data are well correlated, independently, to equations which give the average Nusselt number in terms of the wail spacing to cylinder diameter ratio, t/D, and the Rayleigh number, Ra, for two different values of the wall height to cylinder diameter ratios, H/D=7 and 15.2. For the low Rayleigh numbers considered (Ra<1000), there are certain conditions for the confining walls under which heat transfer from the cylinder is maximum. Results are compared with the reported numerical and/or experimental results...
Effects of confining walls on laminar natural convection from a horizontal cylinder
, Article Proceedings of the Intersociety Energy Conversion Engineering Conference ; Volume 2 , 2000 , Pages 1261-1267 ; 0146955X (ISSN) ; Razi, Y. P ; Sharif University of Technology
2000
Abstract
The laminar natural convection from an isothermal horizontal cylinder confined between vertical walls is investigated by experimental and numerical methods. The experimental and numerical data are well correlated, independently, to equations which give the average Nusselt number in terms of the wall spacing to cylinder diameter ratio, t/D, and the Rayleigh number, Ra, for two different values of the wall height to cylinder diameter ratios, H/D=7 and 15.2. For the low Rayleigh numbers considered (Ra<1000), there are certain conditions for the confining walls under which heat transfer from the cylinder is maximum. Results are compared with the reported numerical and/or experimental results...
Effecive & efficient DSM configuration guidelines for low-cost development of complex systems
, Article Gain Competitive Advantage by Managing Complexity - Proceedings of the 14th International Dependency and Structure Modelling Conference, DSM 2012, 13 September 2012 through 14 September 2012 ; 2012 , Pages 125-137 ; 9783446433540 (ISBN) ; Sharif University of Technology
Institution of Engineering Designers
2012
Abstract
With the proliferation of more complex systems has come the need to find better solutions in both technical and management domains. Such complex systems are usually larger in size, have more parallel operations and contain more complex interfaces (Eisner, 2005). The Design Structure Matrix is a very useful tool in handling such complexities, provided that the system designer can use it properly. This paper addresses how effectiveness & efficiency are defined for a DSM and how these two important characteristics can be achieved. The importance of understanding the solution space in constructing an effective & efficient DSM is discussed and general guidelines are given on configuring the DSM...
An adaptive thresholding approach for image denoising using redundant representations
, Article Machine Learning for Signal Processing XIX - Proceedings of the 2009 IEEE Signal Processing Society Workshop, MLSP 2009, 2 September 2009 through 4 September 2009, Grenoble ; 2009 ; 9781424449484 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
2009
Abstract
A frequently used approach for denoising is the shrinkage of coefficients of the noisy signal representation in a transform domain. Although the use of shrinkage is optimal for Gaussian white noise with complete and unitary transforms, it has already been shown that shrinkage has promising results even with redundant transforms. In this paper, we propose using adaptive thresholding of redundant representations of the noisy image for image denoising. In the proposed thresholding scheme, a different threshold is used for each representation coefficient of the noisy image in an overcomplete transform. In this method, each threshold is automatically set based on statistical properties of the...
Boundary layer solution for the turbulent swirling decay flow through a fixed pipe: SBR at the inlet
, Article International Journal of Engineering Science ; Volume 43, Issue 1-2 , 2005 , Pages 107-120 ; 00207225 (ISSN) ; Saidi, M. H ; Sadeghipour, M. S ; Souhar, M ; Sharif University of Technology
Elsevier Ltd
2005
Abstract
In this study the developing turbulent swirling pipe flow is investigated both numerically and analytically. Governing equations are derived accompanying the boundary layer assumptions. Uniform and solid body rotation (SBR) distributions are taken into account for the axial and tangential velocities at the inlet of the pipe, respectively. Beyond the boundary layers, the flow pattern is considered to be the potential flow. Making use of the fourth-order Runge-Kutta scheme, the numerical solution of the differential equations is obtained. Further more, by simplifying the governing equations for large Rossby number, the analytical solution is performed. The results of numerical and analytical...
Numerical analysis of turbulent swirling decay pipe flow
, Article International Communications in Heat and Mass Transfer ; Volume 32, Issue 5 , 2005 , Pages 627-638 ; 07351933 (ISSN) ; Saidi, M. H ; Sadeghipour, M. S ; Souhar, M ; Sharif University of Technology
2005
Abstract
Turbulent swirling decay pipe flow has been investigated numerically in a vertical straight fixed pipe. The swirling flow is created by means of a rotating honeycomb which produces the solid body rotation at the inlet of the fixed pipe. Since there are no experimental data at the inlet of the fixed pipe; different axi-symmetric approaches may be considered to model the honeycomb effects at the downstream flow. Considering the appropriate approach and using the resulting flow field properties from the exit of the modeled swirl generator which are applied as the inlet boundary condition for the fixed pipe, several high Reynolds turbulence models are used to predict this type of the swirling...
Experimental and numerical hydrodynamic modeling of an underwater manipulator
, Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED ; Volume 256 , 2000 , Pages 291-296 ; 08888116 (ISSN) ; Tehranian, A ; Meghdari, A ; Sadeghipour, M. S ; Sharif University of Technology
2000
Abstract
This paper presents the kinematics and dynamic modeling of a three-link (3-DOF) underwater manipulator where the effects of hydrodynamic forces are investigated. In our investigation, drag and added mass coefficients are not considered as constants. In contrast, the drag coefficient is a variable with respect to all relative parameters. Experiments were conducted to validate the hydrodynamic model for a one degree-of-freedom manipulator up to a three degrees-of-freedom manipulator. Finally, the numerical and experimental results are compared and thoroughly discussed
Miniaturized salting-out liquid-liquid extraction in a coupled-syringe system combined with HPLC-UV for extraction and determination of sulfanilamide
, Article Talanta ; Vol. 121 , April , 2014 , pp. 199-204 ; ISSN: 00399140 ; Khosraviani, M ; Sadegh Amini-Fazl, M ; Sharif University of Technology
2014
Abstract
In salting-out liquid-liquid extraction (SALLE) technique, water-miscible organic solvents are used for extraction of polar analytes from saline solutions. In this study, for the first time, a coupled 1-mL syringes system was utilized to perform a miniaturized SALLE method. Sulfanilamide antibiotic was extracted and determined via the developed method followed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The extraction process was carried out by rapid shooting of acetonitrile as extraction solvent (syringe B) into saline aqueous sample solution (syringe A), and then the shooting was repeated several times at a rate of 1 cycle s-1. Thereby, an extremely large...
Seismic Performance Evaluation of Vertcial Irregular Structures through Nonlinear Time History Analysis
, M.Sc. Thesis Sharif University of Technology ; Mofid, Massoud (Supervisor)
Abstract
Incremental Dynamic Analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. Using IDA , the objective is to study the effect of the irregular distribution of stiffness and strength along the height of a 9 story 3D steel structure model. The reference and each modified structure are hence forced to show the complete spectrum of behavior from elasticity to final global instability, allowing the estimation of capacities for the full range of limit-states and enabling a straightforward comparison without needing to “tune” the structures to the same fundamental period and/or the...
A coarse relative-partitioned index theorem
, Article Bulletin des Sciences Mathematiques ; Volume 153 , 2019 , Pages 57-71 ; 00074497 (ISSN) ; Esfahani Zadeh, M ; Sadegh, A ; Sharif University of Technology
Elsevier Masson SAS
2019
Abstract
It seems that the index theory for non-compact spaces has found its ultimate formulation in the realm of coarse spaces and K-theory of related operator algebras. Relative and partitioned index theorems may be mentioned as two important and interesting examples of this program. In this paper we formulate a combination of these two theorems and establish a partitioned-relative index theorem. © 2019 Elsevier Masson SAS
The effect of additives on anode passivation in electrorefining of copper
, Article Chemical Engineering and Processing: Process Intensification ; Volume 46, Issue 8 , 2007 , Pages 757-763 ; 02552701 (ISSN) ; Yoozbashizadeh, H ; Sadegh Safarzadeh, M ; Sharif University of Technology
2007
Abstract
In copper electrorefining process, some additives are added to the electrolyte to improve the morphology of cathode deposits as well as the quality of products. In the present investigation, the effects of thiourea, glue and chloride ions (as additives) on the passivation of industrial copper anodes under high current densities have been reported. Experiments were conducted at 65 °C; using a synthetic electrolyte containing 40 g/l Cu2+ and 160 g/l H2SO4. Results obtained from chronopotentiometry experiments showed that increasing the concentration of chloride ion leads to increase in passivation time. The results also indicated that from a certain level on, namely 2 ppm, the increase in...
Characterization of interfacial hydrodynamics in a single cell of shaken microtiter plate bioreactors applying computational fluid dynamics technique
, Article Procedia Engineering ; Volume 42 , 2012 , Pages 924-930 ; 18777058 (ISSN) ; Amoabediny, G ; Sadegh Saghafinia, M ; Haji Abbas, M. P ; Sharif University of Technology
2012
Abstract
Development of orbital shaking technology for enhanced mixing with lower mechanical demand has been receiving significant attention since the advent of advanced mixing schemes. Amongst shaken bioreactors, microtiter plates play significant role both for research and industrial purposes due to their capability of handling tiny amount of liquid in parallel experimentations. Detailed understanding of complicated Flow hydrodynamics thus seems to be considered a continual effort, as it is responsible for efficient gas-liquid mass transfer. Computational fluid dynamics (CFD) technique is shown to be a suitable numerical method in particular for discovering concealed flow facts, which can reliably...
Thin Film Thickness Measurement Using Colors of Interference Fringes
, M.Sc. Thesis Sharif University of Technology ; Amjadi, Ahmad (Supervisor)
Abstract
There are several methods for measuring thin film thickness, however, for the analysis of liquid film motors [1] we need a method which is capable of measuring the thickness using a single image of the film. In this work, we use the colors that appear on thin films, such as soup bubbles, which is a result of light interference to calculate the thickness of the layer
Measure for Macroscopic Quantumness via Quantum Coherence and Macroscopic Distinction
, M.Sc. Thesis Sharif University of Technology ; Raeisi, Sadegh (Supervisor)
Abstract
One of the most elusive problems in quantum mechanics is the transition between classical and quantum physics. This problem can be traced back to the Schrodinger's cat. A key element that lies at the center of this problem is the lack of a clear understanding and characterization of macroscopic quantum states. Our understanding of Macroscopic Quantumness relies on states such as the Greenberger-Horne-Zeilinger(GHZ) or the NOON state. Here we take a first principle approach to this problem. We start from coherence as the key quantity that captures the notion of quantumness and demand the quantumness to be collective and macroscopic. To this end, we introduce macroscopic coherence which is the...
Structural Health Monitoring using Bayesian Optimization of the finite element model of structures and Kalman filter
, M.Sc. Thesis Sharif University of Technology ; Bakhshi, Ali (Supervisor)
Abstract
With confidence in the recorded observations, the RLS method no longer estimates the recorded measurements by sensors, i.e. the displacement and speed of the floors, and only estimates the parameters. In contrast, in the EKF method, in addition to estimating the structure's parameters, a more precise estimation of the observations recorded by the sensors has been done by accepting the noise in the recorded observations. These methods, which are based on the Bayesian updating, investigate the two primary sources of uncertainty in a problem: a) measurement noise or observation noise, and b) process noise, which includes modeling errors. In these methodologies, the unknown system parameters,...
Image Enhancement via Sparse Decomposition
, M.Sc. Thesis Sharif University of Technology ; Babaiezadeh, Massoud (Supervisor)
Abstract
Sparse decomposition has recently attracted the attention of many researchers in dierent areas of signal processing. In mathematical viewpoint, sparse decomposition is nding a sparse solution of an Underdetermined System of Linear Equations (USLE). This concept has many applications in dierent signal processing elds including blind sourse separation, optical character recognition and image processing. In this thesis, we investigate the application of sparse decomposition in image denoising. One of the image denoising methods which is related to sparse decomposition concepts is the \transfrom domain method". In this method, the noisy image is rst transformed to another domain, and then noise...
Finding Semi-Optimal Measurements for Entanglement Detection Using Autoencoder Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Raeisi, Sadegh (Supervisor)
Abstract
Entanglement is one of the key resources of quantum information science which makes identification of entangled states essential to a wide range of quantum technologies and phenomena.This problem is however both computationally and experimentally challenging.Here we use autoencoder neural networks to find semi-optimal measurements for detection of entangled states. We show that it is possible to find high-performance entanglement detectors with as few as three measurements. Also, with the complete information of the state, we develop a neural network that can identify all two-qubits entangled states almost perfectly.This result paves the way for automatic development of efficient...
Numerical Analysis and Optimization of A Vortex Tube with Differential Evolution Algorithm
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
The vortex tube is a simple device that injects compressed gas (air) tangentially into the vortex chamber through one or more injection nozzles. After entering, the flow becomes rotational and an axial cold flow goes towards the cold outlet and a peripheral hot flow goes towards the hot outlet. Besides all the different applications of the vortex tube, the main application of this device is cooling. Here, the goal is to optimize the geometry and physical conditions to improve the performance, which is done by using a commercial software and numerical analysis of a vortex tube to understand the flow physics and optimization. In this research, we use experimental and numerical data for...
Grafting of acrylamide onto kappa-carrageenan via γ-irradiation: Optimization and swelling behavior
, Article Radiation Physics and Chemistry ; Volume 77, Issue 2 , 2008 , Pages 131-137 ; 0969806X (ISSN) ; Pourjavadi, A ; Sheikh, N ; Sadegh Amini Fazl, M ; Sharif University of Technology
2008
Abstract
The Taguchi method, a robust experimental design for optimization, was used for the synthesis of a superabsorbent hydrogel network using γ-rays as an initiator, energy source and crosslinker at the same time. Nine different samples of superabsorbent hydrogels were prepared in various conditions from kappa-carrageenan (κC) and acrylamide by γ-irradiation at room temperature. Considering the results of nine trials and according to analysis of variance (ANOVA), a new experimental condition with the concentrations of κC and acrylamide 1.5 g and 0.028 mol (2 g in total volume of 50 mL H2O), respectively, as well as γ-ray at the optimum total dose (7 kGy) was proposed. After preparing the desired...