Multi-objective optimization of piezoelectric microactuator using genetic algorithms

, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 13, Issue PART B , 2009 , Pages 723-730 ; 9780791848746 (ISBN) Esteki, H ; Hasannia, A ; Sharif University of Technology

2009

Abstract

In flex-tensional piezoactuators, due to the low displacement of piezostacks, a compliant mechanism is used to amplify displacement of piezostack. In this paper, optimization of a compliant mechanism with corner-filleted flexure hinges is carried out using real-coded genetic algorithms (GAs) to avoid trapping in local optimums. The objective functions are displacement amplification and stiffness of mechanism and design variables are cross-sectional size and material used. The constraints which are applied on mechanism are based on piezostack dimensions and manufacturing limits. Displacement amplification and stiffness are calculated using strain energy and Castigliano's displacement theorem....

The Impact of Dutch Disease and Sovereign Wealth Funds on the Composition of Oil-Exporting Countries’ Manufacturing Sector

, M.Sc. Thesis Sharif University of Technology Esteki, Omid (Author) ; Nili, Masoud (Supervisor)

Abstract

This research examines the impact of indirect network effects in platforms on the likelihood of success for platform complements. The main question addressed by this study is: How does a larger number of complements in a platform ecosystem, through access to diverse resources and knowledge, influence the enhancement of innovation and the likelihood of success for platform complements? While the expansion of indirect networks creates more opportunities for innovation and access to resources on one hand, it may also lead to negative effects such as increased competition among complements and user confusion on the other. The goal of this research is to provide a comprehensive answer to these...

Optimum design and vibration suppression of a piezoelectric amplified microactuator using FEM analysis

, Article s20th International Microprocesses and Nanotechnology Conference, MNC 2007, Kyoto, 5 November 2007 through 8 November 2007 ; February , 2007 , Pages 378-379 ; 4990247248 (ISBN); 9784990247249 (ISBN) Mahboobi, H ; Shahidi, A ; Pirouzpanah, S ; Esteki, H ; Sarkar, S ; Sharif University of Technology

2007

Abstract

In this research the optimum design of a piezoelectric amplified microactuator has been achieved via equation (1) and sensitivity analysis in FEM simulation software. In addition, for the sake of simplicity and utilizing the FEM software simulation facilities, the control strategy has been embedded in FEM simulation as a programming routine. The simulations showed the efficiency of the proposed controller to suppress the microactuator's undesired vibrations

Trajectory following of a micro motion stage based on closed-loop FEM simulation

, Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 11 PART A , 2008 , Pages 155-158 ; 079184305X (ISBN); 9780791843055 (ISBN) Shahidi, A ; Mahboobi, S. H ; Pirouzpanah, S ; Esteki, H ; Sarkar, S ; Sharif University of Technology

2008

Abstract

Micro motion stages are one of the essential components in field of micro robotics and ultra fine positioning systems. This research presents the optimum design of a 3-DOF micro motion stage and its position control using FEM simulation. This stage to be studied uses a 3 RRR flexure hinge base compliant mechanism driven by three piezoelectric stack actuators to provide micro scale planar motion. First of all parametric modeling of the stage will be fulfilled in ANSYS environment utilizing a commercial piezostack and different types of flexure hinges. Hence the Jacobian matrix will be achieved for each case. The optimum selection of the hinge form will be achieved upon results of the previous...

Trajectory following of a micro motion stage based on closedloop fem simulation

, Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 11 , 2007 , Pages 155-158 ; 079184305X (ISBN) Shahidi, A ; Mahboobi, S. H ; Pirouzpanah, S ; Esteki, H ; Sarkar, S ; ASME ; Sharif University of Technology

American Society of Mechanical Engineers (ASME) 2007

Abstract

Micro motion stages are one of the essential components in field of micro robotics and ultra fine positioning systems. This research presents the optimum design of a 3-DOF micro motion stage and its position control using FEM simulation. This stage to be studied uses a 3 RRR flexure hinge base compliant mechanism driven by three piezoelectric stack actuators to provide micro scale planar motion. First of all parametric modeling of the stage will be fulfilled in ANSYS environment utilizing a commercial piezostack and different types of flexure hinges. Hence the Jacobian matrix will be achieved for each case. The optimum selection of the hinge form will be achieved upon results of the previous...

Synthesize of Graphene Nanoribbons with a Non-Zero Energy Band Gap for Inactivation of Alive Cells Using Infrared Irradiation

, M.Sc. Thesis Sharif University of Technology Emamy, Hamed (Author) ; Akhavan, Omid (Supervisor)

Abstract

Graphene is a one layer atom thickness and zero energy gap so for using it in nano electronic and transistors baised on graphene it's energy gap should be opened.one of the methods for opening graphene band gap is creating nano scale boundaries or synthesize graphene nanoribbons. One of the new methods for graphene nanoribbon synthesize is longitudinal opening of carbon nanotube. In this thesis graphene nanoribbons synthesize with this method and analyze with AFM and Raman spectroscopy. Carbon nanotubes also have energy gap and IR absorption recently they used for living cell destruction. In this thesis we synthesize graphene nanoribbons and analyzing their optical absorption and use it for...

Fabrication of Graphene/TiO2 Nanowalls as Visible Lights Photocatalysts

, M.Sc. Thesis Sharif University of Technology Rahimi, Kourosh (Author) ; Akhavan, Omid (Supervisor)

Abstract

TiO2 is known as a photocatalyst in near UV-Visible light region with better efficiency compared to other semiconductor photocatalysts. Many attempts have been done to increase the efficiency of this photocatalyst. also, application of 2D carbon nanostructures namely graphene for increasing the photocatalytic activity of TiO2 has shown positive results.
In this research, we first synthesized Graphene Oxide (GO) suspension by exfolation of graphite oxide suspension. then we fabricated TiO2 thin films on glass substrates by so-called sol-gel method. finally we fabricate Graphene Oxide/TiO2 nanowalls composite films as a photocatalyst in visible light. X-ray photoelectron spectroscopy...

Fabrication of Graphene-WO3 Nanocomposites as Photocatalyst in the Visible Light Region

, M.Sc. Thesis Sharif University of Technology Choobtashani, Mohammad (Author) ; Akhavan, Omid (Supervisor)

Abstract

WO3 is known as a photocatalyst in the visible light region, but with lower efficiency compared to more interesting semiconductor photocatalysts such as TiO2 and ZnO. Many attempts have been done to increase the efficiency of this photocatalyst by incorporating metal and metal oxide nanoparticles or recently carbon nanotubes.On the other hand, application of graphene, as an unrolled carbon nanotube, for increasing the photocatalytic activity of TiO2 and ZnO has shown positive results. Furthermore, it was reported that such semiconductor photocatalysts (and very recently WO3) can photocatalytically reduce the chemically exfoliated graphene oxide sheets under UV-vis irradiation.
In this...

Synthesis of Graphene Nanosheets for Stem Cells Applications

, M.Sc. Thesis Sharif University of Technology Shahsavar, Mahla (Author) ; Akhavan, Omid (Supervisor)

Abstract

Graphene nanogrids fabricated by graphene nanoribbons obtained through oxidative unzipping of multi-walled carbon nanotubes, used as two-dimensional selective templates for accelerated differentiation of human mesenchymal stem cells (hMSCs), isolated from umbilical cord blood, into osteogenic lineage. The biocompatible and hydrophilic graphene nanogrids showed high actin cytoskeleton proliferations that coinciding with patterns of the nanogrids. The amounts of proliferations found are slightly better than proliferation on hydrophilic graphene oxide (GO) sheets, and significantly higher than non-uniform proliferations on hydrophobic reduced graphene oxide (rGO) sheets and polydimethylsiloxane...

Identifying the risks of Iranian Knowledge BasedFirms Using Fault Tree Analysis (FTA)

, M.Sc. Thesis Sharif University of Technology Sarhadi, Maryam (Author) ; Fattahi, Omid (Supervisor)

Abstract

Knowledge Based Firms are considered to be important for the economic development of a country in regards to both employment growth and innovative activity. The latter is believed to contribute significantly to the increase in productivity and therefore the competitiveness of Iran’s economy. This study contributes to the above literature by investigating the factors that are believed to treat the growth of such firms in Iran. The purpose of this study is to identify functional risks of vital signs monitors via Fault Tree Analysis (FTA) method to use as a guide for manufacturers to identify and control hazards. Therefore, 30 knowledge based firms were selected as sample. Then, based on a...

Synthesis of Graphene from Waste by Chemical Exfoliation and Study of It’s Physical Characteristics

, M.Sc. Thesis Sharif University of Technology Mirsepah, Ali (Author) ; Akhavan, Omid (Supervisor)

Abstract

One atom thick layer of pure carbon in bonded and hexagonal lattice is named graphene. graphene has unique mechanical, optical, thermal and electrical properties and because of these properties has grabbed attention. graphene has been made from high pure graphite by different methods such as CVD(chemical vapor deposition) , chemical exfoliation , micromechanical cleavage and colloidal suspension. through these methods, green methods for synthesis of graphene, using eco-friendly reductants during synthesis of graphene instead of hydrazine and recently using waste(not graphite) are attractive for synthesis of graphene. Following this idea , a group has produced graphene from wastes such as...

The Use of Hydrogen Rich Water for Synthesis of Hydrogenized Graphene and Investigation of Its Properties

, M.Sc. Thesis Sharif University of Technology Ghorbani, Fatemeh (Author) ; Akhavan, Omid (Supervisor)

Abstract

Graphene is a two dimensional lattice which is created from carbon atoms. Having special feature, it has such various medical usage, for example in diagnosing and treating cancer. Adding a particular factor to graphene could improve their efficiency. In comparis on with graphene itself, graphene oxide and reduced graphene oxide are much more successful in diagnosing and treating than others because of their higher hygroscopic. Recent studies state that hydrogenized combinations including hydrogenized graphene show desired results. Due to its higher hygroscopic and the possibility of adherence to the cells, hydrogenized graphene could be very effective in diagnosing and treating the sarcomas....

A Meta Heuristic Approach for Design of a Network System in Mass Customization

, M.Sc. Thesis Sharif University of Technology Puresmaili, Ehsan (Author) ; Fattahi, Omid (Supervisor)

Abstract

This study discusses about mass customization and optimization of supply network in which both goal considering to set the flow of raw material and final product to satisfy the customer demand. The mass customization is more important concept in this study, so that this goal is placed to the first objective. In this research, the model which contained both goal is presented. The model focus on mass customization and try to satisfy various products demand, which constitute 3 kind of speed demands. Each product can satisfy in 3 way: fast, normal, slow.In the first model the new approach present in which the speed affects all of supplying, manufacturing and distributing system. The system try...

Synthesis of Graphene Oxide and Study of its Fluorescence Properties

, M.Sc. Thesis Sharif University of Technology Akbari, Ebrahim (Author) ; Akhavan, Omid (Supervisor)

Abstract

Graphene oxide is a single sheet of Carbon atoms which has been arranged on a two-dimensional honeycomb lattice. Functional groups such as epoxy, carboxyl and carbonyl are located on basal plane and at the edges of graphene oxide and they localize electrons on the surface of graphene oxide and open band gap in its band structure. Pure graphene has zero band gap, so existence of fluorescence properties is unlikely; but graphene oxide has fluorescence properties due to band gap in its band structure. Fluorescence properties of graphene have been used in live cell imaging and drug delivery, so study and increasing of fluorescence properties is significantly important. The purpose of this...

A Novel Reliability Model for Information Technology Web services

, M.Sc. Thesis Sharif University of Technology (Author) ; Fatahi Valilai, Omid (Supervisor)

Abstract

The Internet is often used for communication-based applications such as online banking, stock trading, and shopping where service interruption is unacceptable. Thus, analysis of the impact of the failures of hardware, software, and related services’ performance quality of the service provided to users is of importance to designers and managers in these functions. In this study, we developed a strategy to the design of a dynamic combination of file servers with the aim of providing reliability and SLA. At first, we examine the reasons for the violation of service level in file host services and datacenters, and then we introduce the criteria to measure the violation of service level on the...

Development of a novel solution to enable integration and interoperability for cloud manufacturing

, Article 6th International Conference on Changeable, September 2016 through 6 September 2016 ; Volume 52 , 2016 , Pages 6-11 ; 22128271 (ISSN) Delaram, J ; Fatahi Valilai, Omid ; Sharif University of Technology

Elsevier B. V 2016

Abstract

Nowadays, manufacturing enterprises have been faced with a globalized competitive environment. In this fierce condition, Cloud Manufacturing paradigm emerged as a promising concept for competition. It provides effective solutions and tools for manufacturing enterprises to collaborate in globalized market. The revolution that Cloud Manufacturing has created is based on the redefinition of the classic methods to those which are appropriate for todays' modern and globalized manufacturing environments. In parallel with cloud-based revolution, the expansion of internet-based technologies has been started. These technologies previously have been applied in many fields and resulted in...

Product Portfolio Management Using Life Cycle Considerations

, M.Sc. Thesis Sharif University of Technology Ebrahimian, Mahsa (Author) ; Fattahi, Omid (Supervisor)

Abstract

Today’s organizations always encounter limitations on the way of achieving their goals. Budget constraint, inventory constraints, capital constraints are issues which complicates management decision making.
Global market has enabled manufacturers compete globally. Even position their factories in other countries and use of competitive advantages and other markets demand. This is why decision making in production and manufacturing domain has been complicated. Decision making in production and manufacturing should become faster and more precise in order to keep market competitiveness. Organization should make long term or strategic decisions and short term decisions about keeping the...

Fabricating Graphene Paper and Determining Its Electrical and Mechanical Properties and Using It for Proliferation and Differentiation of Neural Stem Cells

, M.Sc. Thesis Sharif University of Technology Akbar Shirazian, Soheil (Author) ; Akhavan, Omid (Supervisor)

Abstract

Nowadays, tissue engineering and stem cells-based therapies have outlined a promising prospect in neural networks regeneration. But it usually requires biocompatible and conductive scaffolds for culturing neural stem cells and directing their differentiation toward the neurons. Graphene due to its unique physical and chemical properties has attracted much interest in tissue engineering. For this purpose, in this study biocompatible graphene oxide foams have been used for neural stem cell culturing. For the first time, graphene oxide foam were fabricated by precipitation of chemically exfoliated graphene oxide sheets in an aqueous suspension onto the PET substrate at ~80 oC under UV...

Numerical Modeling of Contact-Impact Problems Using Polygonal Finite Element Method

, Ph.D. Dissertation Sharif University of Technology Biabanaki, Omid Reza (Author) ; Khoei, Amir Reza (Supervisor)

Abstract

A Polygonal finite element method without conforming mesh was introduced by the authors for modeling large deformation elastoplastic problems. In this method, the geometry and interfaces of the problem are modeled on a uniform mesh. The boundaries are defined on the uniform background mesh using the level set method. Different polygonal elements will be created at the intersection of the interface and the uniform mesh. Polygonal element shape functions are used for the interpolation. In this paper, the capability of this polygonal finite element approach for modeling large deformational frictionless dynamic contact-impact problems is investigated. Contact interfaces are modeled independent...

Synthesis of Graphene Nanosheets for Application in Biosensors

, M.Sc. Thesis Sharif University of Technology Rahighi Yazdi, Reza (Author) ; Akhavan, Omid (Supervisor)

Abstract

Graphene, the newborn nanomaterial whose unique properties has extensively drawnattention of many scientists in the recent years, is an ideal candidate for sensing applications due to its exclusive properties like extremely high specific surface area, excellent electrical conductivity, andcapability of being easily functionalized. In this research, after reviewing the attempts already performed on detection of DNA, in order to detect the four bases of DNA (G, A, T, and C) via electrochemical approach, graphene nanosheets were synthesized by the popular Hummer’s method and were deposited on a graphite rod by electrophoretic deposition with a vertical preferred orientation. To eliminate the...