Theoretical and Experimental Investigation of Die Swell Phenomenon for Polymer Nano-Composites

, M.Sc. Thesis Sharif University of Technology Khodadadi Yazdi, Mohsen (Author) ; Ramezani Saadat Abadi, Ahmad (Supervisor)

Abstract

This thesis was conducted both numerically and experimentally. In the experimental investigations aqueous solutions of high molecular weight Carboxymethylcellulose (CMC) was used. The experimental set-up was composed of a glass syringe, and a piston which can easily move through the syringe. Different die with aspect ratio ranging from 5.25 to 28.8 can be attached to the syringe. The syringe then is filled with the CMC solution with different weight fractions. Then using a force exerting on the piston, the solution comes out of the die and exiting velocity was calculated from weight of CMC solution that exit from die in a definite time. High quality photographs were taken from extrudate...

Production planning problem with pricing under random yield: CVAR criterion [electronic resource]

, Article Journal of Systems Science and Systems Engineering ; 2014 Eskandarzadeh, S. (Saman) ; Eshghi, Kourosh ; Modarres Yazdi, Mohammad ; Bahramgiri, Mohsen ; Sharif University of Technology

Abstract

In this paper, we address a basic production planning problem with price dependent demand and stochastic yield of production. We use price and target quantity as decision variables to lower the risk of low yield. The value of risk control becomes more important especially for products with short life cycle. This is because, the profit implications of low yield might be unbearable in the short run. We apply Conditional Value at Risk (CVaR) to model the risk. CVaR measure is a coherent risk measure and thereby having nice conceptual and mathematical underpinnings. It is also widely used in practice. We consider the problem under general demand function and general distribution function of...

Simulation of flow of short fiber suspensions through a planar contraction

, Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 579-584 ; 10263098 (ISSN) Khodadadi Yazdi, M ; Ramazani S. A. A ; Kamyabi, A ; Hosseini Amoli, H ; Sharif University of Technology

2012

Abstract

In this study, the flow of a fiber filled viscoelastic matrix through planar contractions is investigated. It was found that by adding fiber to the matrix vortex, the intensity increases. Fiber orientation along "x" and "y" axes was studied too. It was found that fiber orientation could be used for determining the flow regime through the contraction geometry. The rigidity condition of fibers, which needs the trace of the orientation tensor to be unity everywhere in the domain, is correct except near walls and the reentrant corner, which is slightly less than one. In these regions, the stress magnitude is higher, which results in more numerical errors, and which further leads to some error in...

Preparation of Nanoparticles Based on Hyperbranched Polyglycerol as Anti Cancer Drug Delivery Systems

, M.Sc. Thesis Sharif University of Technology Yazdi, Mojtaba (Author) ; Pourjavadi, Ali (Supervisor) ; Adeli, Mohsen (Co-Advisor)

Abstract

Successful formulation development for poor water soluble drugs is a critical, long-standing and challengeable problem in cancer treatment. One of the methods for transporting low-soluble drugs is using nanoparticles which are able to pass through capillary walls of tumor tissues due to their small size. An example of the nanoparticles is micelle systems. Functionalized β-cyclodextrin (β-CD) by hyper branched polyglycerol (HPG) can dissolve low-soluble compounds. This polymer can be used in preparing micelles. In this project, β-cyclodextrin (β-CD) by anionic reactions is initiator for polymerization of glycidol monomer. Hydrophobic cavity of the β-cyclodextrin (β-CD) in placing the phenyl...

Flow of a PTT fluid through planar contractions - Vortex inhibition using rounded corners

, Article ASME 2010 International Mechanical Engineering Congress and Exposition, IMECE 2010, Vancouver, BC, 12 November 2010 through 18 November 2010 ; Volume 7, Issue PARTS A AND B , November , 2010 , Pages 601-607 ; 9780791844441 (ISBN) Khodadadi Yazdi, M ; Ramazani S. A, A ; Hosseini Amoli, H ; Behrang, A ; Kamyabi, A ; Sharif University of Technology

2010

Abstract

Contraction flow is one of important geometries in fluid flow both in Newtonian and non-Newtonian fluids. In this study, flow of a viscoelastic fluid through a planar 4:1 contraction with rounded corners was investigated. Six different rounding ratios (RR =0, 0.125, 0.25, 0.375, 0.438, 0.475, 0.488) was examined using the linear PTT constitutive equation at creeping flow and isothermal condition. Then the resulting PDE set including continuity, momentum, and PTT constitutive equations were implemented to the OpenFOAM software. The results clearly show vortex deterioration with increasing rounding diameter, so that when rounding corner exceeds a critical value, the vortex disappears...

An Investigation on The Effect of Intermediate Deformation Between The Retrogression and Re Aging Process of 7xxx Series of Aluminum Alloys on The Mechanical Properties and Formability of These Alloys

, M.Sc. Thesis Sharif University of Technology Ahmadpour Yazdi, Mohammad Reza (Author) ; Karimi Taheri, Ali (Supervisor) ; Kazeminejad, Mohsen (Supervisor)

Abstract

In this research it has been attempted to suggest a modified retrogression and re- aging heat treatment on the sheet of AA7075 alloy with a thickness of 2 mm. The main aim of the research is to reduce the required duration of RRA process while maintaining the value of the conventional tensile strength achieving by the RRA process. This was performed by adding an intermediate warm rolling deformation during the RRA process. The rolling temperature was 180 °C and the rolling reductions were 30%, 40%, 50%. Moreover, the temperature of 170°C was selected as the re-aging temperature, for which the aging time of 0.5, 1, 1.5, 2, and 2.5 hours were examined. This temperature and times were chosen to...

Designing a Loadcell for a Walker to Measure Upper Extremities’ Forces

, M.Sc. Thesis Sharif University of Technology Khodadadi, Mohammad (Author) ; Zohoor, Hassan (Supervisor)

Abstract

In this project, two bidirectional loadcell are designed and fabricated to be installed on a walker. Then upper extremities’ forces and moments have been obtained. Results can be used for rehabilitation purposes in Spinal Cord Injuries and Cerebral Palsy cases. The method used in this project is as follows: First, since the commercial multidirectional loadcells are too expensive, the loadcell (and an appropriate electronic board) are fabricated. Ultimately, a complete gait analysis by means of VICON motion analysis and using inverse dynamic method has been held to measure upper extremities’ forces and moments in the wrist, elbow and shoulder. The results for a person with Spinal Cord Injury...

An Efficient Hardware Trojan Detector Using On-chip Ring Oscillator

, M.Sc. Thesis Sharif University of Technology Khodadadi, Mohsen (Author) ; Hesabi, Shahin (Supervisor)

Abstract

Nowadays integrated circuits are extremely vulnerable to hardware trojans (HT). Hardware trojans can be injected into the ICs in design or fabricate phase, and damage system’s functionality or security. In this thesis, we first describe hardware trojan definition, classification and types of HTs, negative effects, detection ways and analysis of them. Then we propose a new solution in order to solve the negative points of previous methods

Experimental Investigation of Microjet Engine Anomaly Detection Based on ANN Data Clustering Analysis

, M.Sc. Thesis Sharif University of Technology Khodadadi, Mahyar (Author) ; Saghafi, Fariborz (Supervisor)

Abstract

In this study, the possibility of detecting known and unknown anomalies in a micro jet engine is evaluated. the proposed method is neural network and clustering analysis. The process consists of two main parts, first part is experimental abnormal behavior simulation and second part is validation of proposed detection method. In the first part a micro jet engine (Olympuse HP) were used and we created pre-designed errors in engine normal behavior to record significant changes in its performance. Recorded outputs consist of six different variables: RPM, Exhaust gas temperature, Throttle command, Fuel pump voltage, Thrust and Fuel weight. In the second part, for analyzing data, we used...

The Role of Safety Attitudes and Attitudes Toward Vehicle in Urban Crashes

, M.Sc. Thesis Sharif University of Technology Khodadadi, Ali (Author) ; Kermanshah, Mohammad (Supervisor)

Abstract

Nearly 1.2 million people die in road crashes each year, and as many as 50 million are injured in the world. In Iran, approximately 800 thousand crashes occur annually killing up to 43 people per day. Given that over 90% of accidents are related to human factors, using models that incorporate driver’s attitudes and behavior can be highly predictive of crashes. The main objective of the current research is to examine the impact of drivers’ attitudes on road crashes along with other factors such as socio-demographic characteristics and vehicle type. This study uses data from a self-completed questionnaire among a representative sample of Iranian drivers living in Tehran. The Questionnaire...

Feasibility Study of Rapid Estimation of SF Parameter of Cells Using the Monte Carlo Simulation of Carbon Therapy in Combination with Cascade Feed-forward Neural Network (CFNN) by Bayesian Regularization Learning Algorithm

, M.Sc. Thesis Sharif University of Technology Khodadadi, Rezvan (Author) ; Vosoughi, Naser (Supervisor)

Abstract

Our main goal in this project is to calculate the cell survival fraction (SF) in unhealthy tissue after carbon ion beams are emitted and hit the target tissue. At present, in the stages of carbon therapy, it usually takes a long time to make the necessary calculations for that particular person, and this makes the treatment process progress slowly, but in this project, we intend to address this problem with Eliminating the use of neural network. The main reason is the use of carbon ions to increase efficiency in the treatment of tumors and deep cancerous tissues. To do this project, we first convert the carbon ion energy to the dose absorbed at the desired point. For this phase of the...

Effects of Microstructure and Salinity Concentration on Hydraulic Conductivity of Silty Clay Soils

, M.Sc. Thesis Sharif University of Technology Khodadadi, Saeed (Author) ; Sadeghi, Hamed (Supervisor)

Abstract

Various contaminants and their leachate, when they penetrate into the soil, cause changes in soil microstructure, this change in microstructure leads to changes in soil permeability and volume. In this study, first, the effects of soil microstructure change on the hydraulic conductivity of saturated soil were investigated using the change in initial saturation degree during compaction for compacted samples and the change in sample construction in reconstituted samples. Also, the simultaneous effect of changing the initial microstructure and salt solution on the hydraulic conductivity of saturated silty clay soils using a three-axial permeability device with the ability to measure volume...

The ion streaming effect on weibel instability in the relativistic dense plasma

, Article Contributions to Plasma Physics ; Volume 57, Issue 8 , 2017 , Pages 351-356 ; 08631042 (ISSN) Khodadadi Azadboni, F ; Mahdavi, M ; Sharif University of Technology

2017

Abstract

The Weibel instability plays an important role in stopping hot electrons and energy deposition mechanism in fast ignition of inertial fusion process. In this paper, the ion Weibel instability in counter propagating electron-ion plasmas is investigate. The obtained results show that the growth rate of Weibel instability will be decreased about 40% with the anisotropy velocity as vxe = 2vze = 20; the ion density ratio, b = n0i1/n0i2, and density gradient, are increasing 50 and 90% respectively. The ion streaming in density gradient of dense plasma leads to increasing the Weibel instability growth rate and its amplification through ion streaming in the large wavenumber. The maximum unstable...

Numerical Solution of Hypersonic Axisymmetric Flows Including Real Gas Effects Using Compact Finite-Difference Scheme

, M.Sc. Thesis Sharif University of Technology Khodadadi, Polin (Author) ; Hejranfar, Kazem (Supervisor)

Abstract

The numerical solution of the parabolized Navier-Stokes (PNS) equations for accurate computation of hypersonic axisymmetric flowfield with real gas effects is obtained by using the fourth-order compact finite-difference method. The PNS equations in the general curvilinear coordinates are solved by using the implicit finite-difference algorithm of Beam and Warming type with a high-order compact accuracy. A shock fitting procedure is utilized in the compact PNS scheme to obtain accurate solutions in the vicinity of the shock. To stabilize the numerical solution, numerical dissipation term and filters are used. The main advantage of the present formulation is that the basic flow variables...

Analysis and Modeling of User Behavior over Social Media

, Ph.D. Dissertation Sharif University of Technology Khodadadi, Ali (Author) ; Rabiee, Hamid Reza (Supervisor)

Abstract

Nowadays many of us spend a big part of our daily times on social media.One of the most important research problems in social media analysis is how to engage users. The trace of user activity over these websites is a valuable resource for user understanding and engagement, but this data is very huge and unstructured. An approach to deal with this problem is user behavior modeling. In this process, first a behavioral model is considered for users, then using the activity data and the behavioral model, some parameters are learned. Finally, using the learned parameters, a user profile is constructed for each user. This profile can be used for user engagement and many other applications....

Synthesis and structure activity relationship of pyridazine-based inhibitors for elucidating the mechanism of amyloid inhibition

, Article Chemical Research in Toxicology ; Volume 31, Issue 10 , 2018 , Pages 1092-1104 ; 0893228X (ISSN) Kalhor, H. R ; Nazari Khodadadi, A ; Sharif University of Technology

American Chemical Society 2018

Abstract

Conformational diseases, constituting a large number of diseases, have been connected with protein misfolding, leading to aggregation known as amyloid fibrils. Mainly due to the lack of detailed molecular mechanisms, there has not been an effective drug to combat amyloid-associated diseases. Recently, a small organic pyridazine-based molecule (RS-0406) has shown significant reductions in amyloid fibrils in both in vitro and in vivo animal studies. However, no information on molecular details of inhibition for the small molecule has been reported. In this work, we have decided to explore structure-activity relationship of pyridazine-based compounds to investigate structural parameters for...

Generation of attosecond electron bunches by the relativistic Weibel instability

, Article Physics of Plasmas ; Volume 25, Issue 1 , 2018 ; 1070664X (ISSN) Khodadadi Azadboni, F ; Sadighi Bonabi, R ; Sharif University of Technology

American Institute of Physics Inc 2018

Abstract

The relativistic Weibel instability and temperature anisotropy can generate electron bunches of attosecond duration which makes it an attractive method for the generation and amplification of tunable ultrashort pulses. In this paper, the effect of the relativistic Weibel instability and temperature anisotropy on generating attosecond electron bunches is investigated. Calculations show that with the reduction relativistic parameter, γ, by a factor of 2, increasing 14.6% of the relativistic Weibel instability leads to about 62% reduction of the nanobunching gain saturation time and the density perturbation generated by the temperature anisotropy and the relativistic Weibel instability. The...

Preparation of Titania based solid strong acid and study of its catalytic activity in esterification of Phthalic anhydride and Sebacic acid

, Article Materials Letters ; Volume 60, Issue 6 , 2006 , Pages 715-719 ; 0167577X (ISSN) Khodadadi Moghaddam, M ; Gholami, M. R ; Sharif University of Technology

2006

Abstract

Esterification of Phthalic anhydride with 2-Octanol and Sebacic acid with Ethanol has been studied in the presence of Sulfated Titania. This study showed that Sulfated Titania has strong catalytic effect on esterification reactions. The effect of some factors such as reaction temperature, molar ratio of acid to alcohol, amount of catalyst used, reaction time, calcination temperature, drying temperature and calcination atmosphere has been investigated. Equilibrium composition achieved in 80 min for Diethyl Sebacate and 20 min for Dioctyl Phthalate in various conditions. © 2005 Elsevier B.V. All rights reserved

A Heuristic Security-Aware Task Scheduling Algorithm in Computational Grids

, M.Sc. Thesis Sharif University of Technology Khodadadi, Farzad (Author) ; Movaghar, Ali (Supervisor)

Abstract

Computational grids consist of hardware and software infrastructures which can provide end users with the power of computational networks in a ubiquitous and cheaper manner. In fact, computational grids provide the ability to use the computational power of geographically distributed and heterogeneous resources. One of the new challenges facing researchers in this area involves security in grid environment which is somehow hard to achieve, because of the distributed nature of grid resources and fast changes in resource availabilities. Since availability, integrity and confidentiality are key factors of security and system’s fault tolerance capability is directly related to resource...

Experimental study of Silver, Zinc and Copper ablation by Nd:YAG laser

, M.Sc. Thesis Sharif University of Technology Khodadadi Daryan, Monireh (Author) ; Saddighi, Rasoul (Supervisor)

Abstract

In this project, production of nano and micro particles with laser ablation of zinc, silver and copper sheet metals in the liquid medium has been experimentally studied. For this aim, homemade Nd:YAG pulsed laser at 1064nm wavelength, 60μs pulses with excellent stability with energies up to 700mj is used. By changing the pulse intensity on the target surface, the parameters such as size, shape and optical properties of nano and micro particles are studied by UV-visible spectroscopy, DLS, and SEM techniques. In this work, by microsecond pulses of Nd:YAG and using measuring devices such as Coherent power /energy meter, the appropriate optical table, the related experiments are implemented....