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Curcumin incorporated PVA-borax dual delivery hydrogels as potential wound dressing materials—Correlation between viscoelastic properties and curcumin release rate
, Article Journal of Applied Polymer Science ; Volume 135, Issue 45 , 2018 ; 00218995 (ISSN) ; Pircheraghi, G ; Bagheri, R ; Sharif University of Technology
John Wiley and Sons Inc
2018
Abstract
Poly(vinyl alcohol) (PVA) is a biocompatible polymer which can be physically crosslinked by Borax to form hydrogel. PVA-Borax (PB) hydrogel is a promising candidate for drug delivery system. Therefore, it is necessary to find the quantitative relationship between drug release rate and network structure of PB hydrogels to predict and control drug release rate. In this work, at first step the optimum ratio of Borax: PVA was determined by studying the interactions between PVA chains and Borax molecules by means of Fourier transform infrared spectroscopy, while viscoelastic properties of prepared PB hydrogels were measured in the oscillatory shear flow field. In the following, curcumin as a...
Effect of Major Principal Stress Direction Rotation on Cyclic Behavior of Dense Sand Using Dynamic Hollow Cylinder Aparratus
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
In the past years a lot of research has been done on effects of different parameters on dynamic behavior of soils. According to these studies, principal stress direction rotation and intermediate principal stress coefficient have a major effect on monotonic behavior of soils, but more studies needed for observingtheir effect on dynamic behavior of soils.
In recent study undrained isotropic consolidated specimens of dense Babolsar sand subjected to α changes using dynamic hollow cylinder apparatus and the inner and outer cell pressure kept constant so that b was relative to α changes.
Fisrt series of testswere done to find an appropriate value for induced cyclic deviator stress. The...
In recent study undrained isotropic consolidated specimens of dense Babolsar sand subjected to α changes using dynamic hollow cylinder apparatus and the inner and outer cell pressure kept constant so that b was relative to α changes.
Fisrt series of testswere done to find an appropriate value for induced cyclic deviator stress. The...
Tailoring Software Testing Techiques for Product Line Engineering
, M.Sc. Thesis Sharif University of Technology ; Mirian-Hosseinabadi, Hassan (Supervisor)
Abstract
In industry it is usual to develop a family of similar software instead of a single one. Software product-line (SPL) engineering or family-based software engineering is an approach that tries to minimize needed effort and time-to-market and maximize quality of manufactured products through strategic planning for maximizing reuse among members of the family. On the other hand it is known that testing software is an indivisible part of software development process which requires considerable time and effort. With large number of products created from an SPL, it is obvious that testing should be conducted in such a way that needed effort does not maintain a linear relationship with number of...
The Study on Relationship between Viscoelastic Properties and Drug Release of Wound Dress Polyvinyl Alcohol Hydrogel
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
Abstract
Wound is a defect or failure in the skin texture which occurs as a result of physical or heat injuries or physiological conditions. The wound dress as a temporary cover can improve wound healing process and due to the unique properties, hydrogels have become appropriate choice for this application. Hydrogel’s structure allows drug to be loaded in the wound dress. Hydrogel wound dress should have adequate fluidity to cover wound’s bed and make full contact with the skin. Sufficient cohesion and strength is also necessary to allow the wound dress to remove from wound completely. Therefore, the study on the viscoelastic properties of hydrogel is important. In this study, polyvinyl alcohol...
Parametric Investigation on Microstructure and Mechanical Properties of Ultrasonic Spot welded Aluminium and Copper Sheets
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossain (Supervisor) ; Abedini, Rezvan (Co-Supervisor)
Abstract
Ultrasonic metal welding is a solid state welding process and is widely used in welding the connections of lithium-ion battery batteries in hybrid and plug-in hybrid vehicles. This welding process has advantages over fusion welding processes such as; Shorter time, no heat affected area, optimal energy consumption, cheaper equipment and no harm to the environment. The aim of this study was to investigate the effect and optimization of time, normal pressure and oscillation amplitude parameters in order to achieve the maximum tensile-shear test force and T-peel test in the dissimilar welding of 1050 aluminum and copper (purity above 99.9%). In order to achieve the optimal state of welding...
Investigation of Operating Parameters for Thorium Adsorption from Wastewater by Using of Radiated Grafting Polymeric Adsorbents in Packed Bed Column
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohamad (Supervisor) ; Torab Mostaedi, Meysam (Supervisor) ; Asadollahzadeh, Mehdi (Co-Supervisor) ; Torkaman, Rezvan (Co-Supervisor)
Abstract
Today, the pollution of heavy metals in wastewater and surface waters, which is a global environmental problem, has increased with the expansion of various industrial activities. Heavy metals cause serious health problems due to their accumulation in human and animal tissues. Thorium, is a radioactive element with an atomic number of 90 that is widely used in the optics, aerospace, metallurgy and chemical industries, in the manufacture of high-strength alloys, in UV photocells, and especially in the nuclear industry. The primary sources of radioactive wastewater include nuclear power plants, nuclear energy industry research centers, medical institutions, industrial production, universities,...
Synthesis and Characterization of Polymer Nanofibers Modified by Using of Radiated Grafting for Adsorption of Molybdenum Ions from Aqueous Solution
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohammad (Supervisor) ; Asadollahzadeh, Mehdi (Supervisor) ; Torkaman, Rezvan (Co-Supervisor) ; Torab Mostaedi, Meysam (Co-Supervisor)
Abstract
Molybdenum is one of the important elements of the intermediary metal with atomic number 42, which is used in various industries, but among the important uses of this metal in the nuclear industry, we can mention the presence of this element in the production of yellow cake as an impurity and also as a precursor for the production of radiopharmaceuticals. It is one of the impurities that remain in all stages of yellow cake production along with uranium, and the high presence of this element causes the centrifuges to become unbalanced during the injection of "U" "F" _"6" gas, and on the other hand, technetium, the main ingredient in the production of radiopharmaceuticals, It comes from the...
Semi-IPN carrageenan-based nanocomposite hydrogels: Synthesis and swelling behavior
, Article Journal of Applied Polymer Science ; Volume 118, Issue 5 , 2010 , Pages 2989-2997 ; 00218995 (ISSN) ; Marandi, G. B ; Pourjavadi, A ; Kiani, G ; Sharif University of Technology
2010
Abstract
Inclusion of nano-clays into hydrogels is an efficient approach to produce nanocomposite hydrogels. The introduction of nano-clay into hydrogels causes an increase in water absorbency. In the present work, Nanocomposite hydro-gels based on kappa-carrageenan were synthesized using sodium montmorillonite as nano-clay. Acrylamide and meth-ylenebisacrylamide were used as monomer and crosslinker, respectively. The structure of nanocomposite hydrogels was investigated by XRD and SEM techniques. Swelling behavior of nanocomposite hydrogels was studied by varying clay and carrageenan contents as well as methylenebisacrylamide concentration. An optimum swelling capacity was achieved at 12% of sodium...
Comparison between isothermal and non-isothermal fatigue behavior in a cast aluminum-silicon-magnesium alloy
, Article Strength of Materials ; Volume 47, Issue 6 , November , 2015 , Pages 840-848 ; 00392316 (ISSN) ; Winter, G ; Farrahi, G. H ; Sharif University of Technology
Springer New York LLC
2015
Abstract
In the present study, the out-of-phase thermomechanical fatigue (OP-TMF) behavior of a cast aluminum-silicon-magnesium alloy, the A356.0 alloy which has been widely used in diesel engine cylinder heads, is compared to room-temperature and high-temperature low cycle fatigue (RT-, HT-LCF) behaviors. For this purpose, strain/temperature-controlled isothermal and non-isothermal fatigue tests were performed based on realistic loading conditions in cylinder heads. Fatigue tests results showed that the plastic strain increased during cycles under constant mechanical strain amplitude, while the specimen failed. Under LCF loadings, the cyclic hardening occurred at low temperatures for the A356.0...
Machine learning in energy economics and finance: A review
, Article Energy Economics ; Volume 81 , 2019 , Pages 709-727 ; 01409883 (ISSN) ; Creamer, G. G ; Rafizadeh, N ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Machine learning (ML) is generating new opportunities for innovative research in energy economics and finance. We critically review the burgeoning literature dedicated to Energy Economics/Finance applications of ML. Our review identifies applications in areas such as predicting energy prices (e.g. crude oil, natural gas, and power), demand forecasting, risk management, trading strategies, data processing, and analyzing macro/energy trends. We critically review the content (methods and findings) of more than 130 articles published between 2005 and 2018. Our analysis suggests that Support Vector Machine (SVM), Artificial Neural Network (ANN), and Genetic Algorithms (GAs) are among the most...
Fault-tolerant earliest-deadline-first scheduling algorithm
, Article 21st International Parallel and Distributed Processing Symposium, IPDPS 2007, Long Beach, CA, 26 March 2007 through 30 March 2007 ; 2007 ; 1424409101 (ISBN); 9781424409105 (ISBN) ; Miremadi, S. G ; Deconinck, G ; Sharif University of Technology
2007
Abstract
The general approach to fault tolerance in uniprocessor systems is to maintain enough time redundancy in the schedule so that any task instance can be re-executed in presence of faults during the execution. In this paper a scheme is presented to add enough and efficient time redundancy to the Earliest-Deadline-First (EDF) scheduling policy for periodic real-time tasks. This scheme can be used to tolerate transient faults during the execution of tasks. We describe a recovery scheme which can be used to re-execute tasks in the event of transient faults and discuss conditions that must be met by any such recovery scheme. For performance evaluation of this idea a tool is developed. © 2007 IEEE
Addressing NoC reliability through an efficient fibonacci-based crosstalk avoidance codec design
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 18 November 2015 through 20 November 2015 ; Volume 9530 , 2015 , Pages 756-770 ; 03029743 (ISSN); 9783319271361 (ISBN) ; Miremadi, S. G ; Wang, G ; Perez, G. M ; Zomaya, A ; Li, K ; Sharif University of Technology
Springer Verlag
2015
Abstract
The reliable transfer in Network on Chips (NoCs) can be threatened by crosstalk fault occurring in wires. Crossstalk fault is due to inter-wire coupling capacitance that based on the patterns of transitions appearing on the wires, significantly limits the reliability of NoCs. Among these transitions, 101 and 010 bit patterns impose the worst crosstalk effects to wires. This work intends to increase the reliability of NoCs against crosstalk faults by applying an improved Fibonacci-based numeral system, called Doubled-Penultimate Fibonacci (DP-Fibo). In the DP-Fibo coding algorithm, code words without ‘101’ and ‘010’ bit patterns are produced to reduce crosstalk faults. Experimental results...
Prediction by Genetic Algorithm and measurement by center hole drilling of residual stresses of MAG weldment
, Article Advanced Materials Research, 2 November 2008 through 5 November 2008 ; Volume 83-86 , 2010 , Pages 738-745 ; 10226680 (ISSN) ; 0878492976 (ISBN); 9780878492978 (ISBN) ; Majzoobi, G. H ; Fadaee, A ; Sharif University of Technology
2010
Abstract
In the present work, specimens were cut out from St-37 plates with 19 mm thickness. The thickness of plates was reduced to 12.5 mm by milling and grinding operations. Then a standard V-shaped fillet was made on one edge of the plates. Two plates were butt-welded by standard metal arc gas (MAG) welding process. Residual stresses induced by welding were measured on 20 specimens by centre hole drilling. Load controlled axial fatigue tests were carried out to determine the fatigue life of specimens. Crack growth rates were obtained from experiment. Fractography of specimens was performed. Genetic Algorithm (GA) was employed for prediction of residual stress value in weldments using the crack...
Solutions for the Double Sine-Gordon equation by Exp-function, Tanh, and extended Tanh methods
, Article Numerical Methods for Partial Differential Equations ; Volume 26, Issue 2 , 2010 , Pages 384-398 ; 0749159X (ISSN) ; Davodi, A. G ; Davodi, A. G ; Sharif University of Technology
2010
Abstract
In this work, we implement some analytical techniques such as the Exp-function, Tanh, and extended Tanh methods for solving nonlinear partial differential equation, which contains sine terms, its name Double Sine-Gordon equation. These methods obtain exact solutions of different types of differential equations in engineering mathematics
Probabilistic analysis of welding residual stress on fatigue crack growth
, Article Arabian Journal for Science and Engineering ; Volume 34, Issue 1 C , 2009 , Pages 195-205 ; 13198025 (ISSN) ; Farrahi, G. H ; Fadaee, A ; Sharif University of Technology
2009
Abstract
The qualitative effects of residual stress parameters on fatigue crack growth are investigated using Monte Carlo probabilistic analysis technique. These parameters include the maximum residual stress,σ0, half-width of the tensile residual stress region, b, and the redistribution of residual stress parameter, β. A normal distribution is assumed for all parameters considered in the investigation and fatigue life is determined using Forman equation. The results indicate that: (i) fatigue life decreases nonlinearly if the mean of random maximum residual stress and the half-width of tensile residual stress region increases; (ii) fatigue life increases nonlinearly if the rate of residual stress...
Influence of residual stress on fatigue life of st-37 butt-mag weldment
, Article 12th International Conference on Metal Forming, METAL FORMING 2008, Krakow, 21 September 2008 through 24 September 2008 ; Volume 79, Issue 2 , 2008 , Pages 280-287 ; 16113683 (ISSN) ; Majzoobi, G. H ; Fadaee, A ; Sharif University of Technology
Wiley-VCH Verlag
2008
Abstract
In this paper residual stresses induced by butt metal arc gas welding (MAGW), in accordance with ASTM E837, are determined by hole drilling. The results are analyzed by probabilistic methods. Also, the effect of fatigue life on relaxation of welding residual stress is investigated. The specimens are tested to measure fatigue life and crack growth rates in accordance with ASTM E466 for force controlled amplitude axial fatigue testing. © 2008 Verlag Stahleisen GmbH, Düsseldorf
Effect of contact geometry on fretting fatigue life of aluminium alloy 2024-T3
, Article Indian Journal of Engineering and Materials Sciences ; Volume 12, Issue 4 , 2005 , Pages 331-336 ; 09714588 (ISSN) ; Majzoobi, G. H ; Chinekesh, H ; Sharif University of Technology
2005
Abstract
The effect of contact geometry on fretting fatigue life was investigated by experiments and numerical simulation. The experiments were conducted for flat and cylindrical pads under the same contact normal force. The post-test examinations including crack growth measurements and fractography were carried out using optical and scanning electron microscopy (SEM). Numerical simulations of pad-specimen assembly with and without crack were performed using a finite element (FE) analysis. The experimental study revealed that the rate of crack growth was higher at the early stages of fretting fatigue for cylindrical pads. This stage corresponds to a higher KII for cylindrical contact model. After...
Investigation of the temperature and density dependences of the effective pair potential parameters using variational theory
, Article International Journal of Thermophysics ; Volume 25, Issue 1 , 2004 , Pages 187-203 ; 0195928X (ISSN) ; Parsafar, G. A ; Mansoori, G. A ; Sharif University of Technology
Kluwer Academic/Plenum Publishers
2004
Abstract
A variational theory (VT), in which the potential energy of a real system is evaluated relative to the hard-sphere system, was used to investigate the medium's effects on the pair potential parameters. By adding the medium's effects to the isolated pair potential, the concept of an 'effective pair potential' (EPP) was introduced. The EPP parameters were compared with those of the average effective pair potential (AEPP) for Ar, which showed the importance of the medium effects and the long range interactions of the AEPP in dense fluids. The study showed that the depth parameter of the AEPP is much larger than that of the EPP
Thermo-mechanical behaviours of light alloys in comparison to high temperature isothermal behaviours
, Article Materials at High Temperatures ; Vol. 31, issue. 1 , 2014 , pp. 12-17 ; ISSN: 09603409 ; Farrahi, G. H ; Winter, G ; Eichlseder, W ; Sharif University of Technology
2014
Abstract
In this article, out-of-phase thermo-mechanical fatigue (TMF) behaviours of light alloys were investigated in comparison to their high temperature low cycle fatigue (LCF) behaviours. For this objective, strain based fatigue tests were performed on the A356 aluminium alloy and on the AZ91 magnesium alloy. Besides, TMF tests were carried out, where both strain and temperature changed. The fatigue lifetime comparison demonstrated that the TMF lifetime was less than that one under LCF loadings at elevated temperatures for both light alloys. The reason was due to severe conditions in TMF tests in comparison to LCF tests. The temperature varied in TMF test but it was constant under LCF loadings....
Fatigue lifetime of AZ91 magnesium alloy subjected to cyclic thermal and mechanical loadings
, Article Materials and Design ; Vol. 53, issue , 2014 , pp. 639-644 ; ISSN: 02613069 ; Farrahi, G. H ; Winter, G ; Eichlseder, W ; Sharif University of Technology
2014
Abstract
In the present paper, thermo-mechanical fatigue (TMF) and low cycle fatigue (LCF) or isothermal fatigue (IF) lifetimes of a cast magnesium alloy (the AZ91 alloy) were studied. In addition to a heat treatment process (T6), several rare elements were added to the alloy to improve the material strength in the first step. Then, the cyclic behavior of the AZ91 was investigated. For this objective, strain-controlled tension-compression fatigue tests were carried out. The temperature varied between 50 and 200. °C in the out-of-phase (OP) TMF tests. The constraint factor which was defined as the ratio of the mechanical strain to the thermal strain, was set to 75%, 100% and 125%. For LCF tests,...