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bonakdar-shirazi--ashkan
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Total 121 records
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor) ; Feyzbakhsh, Alireza (Supervisor)
Abstract
Entrepreneurship is a process that requires high motivation for success. Self-efficacy is to believe the person's ability to organize and carry out certain types of activities to produce specific outcomes. Thus helping to increase self-efficacy beliefs in people who have attempted to entrepreneurship can increase their chances of success. On the other hand Self-leadership has been defined as “the process” of influencing oneself to establish the self-direction and self-motivation needed to perform. And include three major strategies named Behavioral focused strategies, Intrinsic motivation (Natural Reward) strategies, Constructive thought pattern strategies and some specific behaviors in each...
Power Reduction Through Efficient Serial Transmission in NoCs
, M.Sc. Thesis Sharif University of Technology ; Hessabi, Shahin (Supervisor)
Abstract
With progress in integrated circuits technology, on chip systems have become operational, and after that, onchip network are as solutions to improve onchip connections and also its scalability. With improving technology, the number of cores on chips can be more, that it causes increasing importance of produced problems by parallel links. Serial links are one of the methods to decrease these problems. Serial links have some advantages in compare with parallel links in some aspects like: clock pulse skew, cross talk, area cost, difficulties in wiring and synchronizing clock pulse signals. But any way, problems such as high operational frequency and complicated serializer and deserializer...
Effect of centrifugal force on frequency characteristic of rotating hollow cylinders using a newly designed cylindrical super element
, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 10716947 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Ahmadian, M. T ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
A sixteen node cylindrical super element is presented for evaluating the free vibration characteristics of a rotating laminated cylinder with conventional boundary conditions. It is shown that the natural frequencies are affected considerably when the centrifugal force is also taken into account. The vibration frequencies of rotating finite cylinder, obtained by conventional finite element are used to evaluate the accuracy of this approach. The special case of a stationary cylinder with zero spinning velocity is also considered as a check on this method. Results indicate only few number of cylindrical super elements are capable of predicting the natural frequency of the rotating cylinder...
Sustainable-Resilient Supplier Selection Through Fuzzy Multi-Criteria Decision Making Approaches
, M.Sc. Thesis Sharif University of Technology ; Akbari Jokar, Mohammad Resa (Supervisor) ; Memari, Ashkan (Co-Supervisor)
Abstract
Today, with the expansion of business relations at international levels, there are many organizations that operate in global supply chains. Activities at such levels face new types of challenges in various fields of "supply chain management" pillars, of which "supplier selection" is one of them. The possibility of unexpected events, the need to comply with environmental protection laws, as well as the need to take into account social considerations, are among the things that have increased by being in larger supply chains, making it challenging to provide the basic resources needed in such chains and forcing their managers to considering considerations other than what they have always...
Application of a new cylindrical element formulation in finite element structural analysis of FGM hollow cylinders
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 14 , 2009 , Pages 21-25 ; 9780791848753 (ISBN) ; Taghvaeipour, A ; Bonakdar, M ; Sharif University of Technology
2009
Abstract
Functionally graded materials are advanced composite materials consisting two or more material ingredients that are engineered to have a continuous spatial variation of properties. There are a few analytical methods available to solve the governing equations of FGM made structures, confined to some specific and limited shapes, loadings and boundary conditions. Hence the numerical methods such as FEM are used to treat these materials. In previous studies the finite element method was used to solve thin walled FG structures like shells and plates by modification of the conventional shell and plate elements. Solving the thick walled FG structures confronts some difficulties. One of the methods...
Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 66, Issue 3 , 2017 , Pages 105-114 ; 00914037 (ISSN) ; Tamjid, E ; Simchi, A ; Bonakdar, S ; Stroeve, P ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
In this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100–250 µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the...
A microfabricated platform for the study of chondrogenesis under different compressive loads
, Article Journal of the Mechanical Behavior of Biomedical Materials ; Volume 78 , 2018 , Pages 404-413 ; 17516161 (ISSN) ; Jahanbakhsh, A ; Saidi, M. S ; Bonakdar, S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Microfluidic devices are beneficial in miniaturizing and multiplexing various cellular assays in a single platform. Chondrogenesis is known to pertain to chemical, topographical, and mechanical cues in the microenvironment. Mechanical cues themselves have numerous parameters such as strain magnitude, frequency, and stimulation time. Effects of different strain magnitudes on the chondrogenic differentiation of adult stem cells have not been explored thoroughly. Here, a new multilayer microdevice is presented for the unidirectional compressive stimulation of cells in a three-dimensional cell culture. Numerical simulations were performed to evaluate and optimize the design. Results showed a...
Improvement to speech-music discrimination using sinusoidal model based features
, Article Multimedia Tools and Applications ; Volume 50, Issue 2 , November , 2010 , Pages 415-435 ; 13807501 (ISSN) ; Ghaemmaghami, S ; Sharif University of Technology
2010
Abstract
This paper addresses a model-based audio content analysis for classification of speech-music mixed audio signals into speech and music. A set of new features is presented and evaluated based on sinusoidal modeling of audio signals. The new feature set, including variance of the birth frequencies and duration of the longest frequency track in sinusoidal model, as a measure of the harmony and signal continuity, is introduced and discussed in detail. These features are used and compared to typical features as inputs to an audio classifier. Performance of these sinusoidal model features is evaluated through classification of audio into speech and music using both the GMM (Gaussian Mixture Model)...
Audio classification based on sinusoidal model: a new feature
, Article 2008 IEEE Region 10 Conference, TENCON 2008, Hyderabad, 19 November 2008 through 21 November 2008 ; 2008 ; 1424424089 (ISBN); 9781424424085 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
2008
Abstract
In this paper, a new feature set is presented and evaluated based on sinusoidal modeling of audio signals. Duration of the longest sinusoidal model frequency track, as a measure of the harmony, is used and compared to typical features as input into an audio classifier. The performance of this sinusoidal model feature is evaluated through classification of audio to speech and music using both the GMM and the SVM classifiers. Classification results show the proposed feature, which could be used for the first time in such an audio classification, is quite successful in speech/music classification. Experimental comparisons with popular features for audio classification, such as HZCRR and LSTER,...
Fabrication of biocompatible titanium scaffolds using space holder technique
, Article Journal of Materials Science: Materials in Medicine ; Volume 23, Issue 10 , 2012 , Pages 2483-2488 ; 09574530 (ISSN) ; Sadrnezhaad, S. K ; Shokrgozar, M. A ; Bonakdar, S ; Sharif University of Technology
Springer
2012
Abstract
Open-pore titanium scaffolds were fabricated by sintering of compressed mixtures of TiH1.924 and urea. Spherical and irregular shaped space holders were used to investigate the effect of pore shape on cellular behavior. After removal of the space holder, the shape of the spacers was replicated to the pores. Average diameter of the pores was in the range of 300-600 lm. SEM images showed that titanium hydride resulted in higher surface roughness and larger micro porosities than pure titanium. In vitro evaluationswere carried out by using MTT assay, measuring alkaline phosphatase activity and alizarin red staining in flow perfusion bioreactor for cell culture. Observations revealed excellent...
Hybrid cross-linked hydrogels based on fibrous protein/block copolymers and layered silicate nanoparticles: Tunable thermosensitivity, biodegradability and mechanical durability
, Article RSC Advances ; Volume 6, Issue 67 , 2016 , Pages 62944-62957 ; 20462069 (ISSN) ; Simchi, A ; Mehrjoo, M ; Shokrgozar, M. A ; Bonakdar, S ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
Stimuli responsive polymer hydrogels have sparked a considerable interest for biomedical applications. In this work, we present a novel injectable thermal responsive hydrogel based on mineral nanoclay (LAPONITE®), wool-derived fibrous protein (keratin), triblock copolymer (Pluronic), and chitosan biopolymer with potential applications for articular cartilage tissue engineering. Genipin was utilized as a natural crosslinker. The formation of polymer conjugates between the components is confirmed by FTIR and 1H NMR spectroscopy. The nanocomposite hydrogel contains interconnected pores within the hydrogel network and the size of the pores is found to reduce at higher crosslinking density and on...
Solving the minimum toll revenue problem in real transportation networks
, Article Optimization Letters ; 2014 ; ISSN: 18624472 ; Aashtiani, H. Z ; Sharif University of Technology
2014
Abstract
As a means to relieve traffic congestion, toll pricing has recently received significant attention by transportation planners. Inappropriate use of transportation networks is one of the major causes of network congestion. Toll pricing is a method of traffic management in which traffic flow is guided to proper time and path in order to reduce the total delay in the network. This article investigates a method for solving the minimum toll revenue problem in real and large-scale transportation networks. The objective of this problem is to find link tolls that simultaneously cause users to efficiently use the transportation network and to minimize the total toll revenues to be collected. Although...
Atom Transfer Radical Polymerization of Acryl Amide in Reverse Suspension
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Atom transfer radical polymerization (ATRP) is a convenient approach to synthesis of polymer with narrow molecular weight distribution. ATRP of acrylamide (AAm) is taken into consideration because of the intrinsic properties of acrylamide such as water solubility and biocompatibility. As reported in many recent works, polymerization of acrylamide by this method didn’t provide monomodal molecular weight distributions. In best condition with strong ligands such as Me4Cyclam, polymerization was carried out in a short time with high yield but polymerization was not highly controlled. It was shown that polymerization of acrylamide under typical ATRP condition displayed a much lower ATRP...
Investigation of Potential Failure Modes of Electric Submersible Pumps and Propose New Methods for Fault Diagnosis and Condition Monitoring of
Electric Submersible Pump
,
M.Sc. Thesis
Sharif University of Technology
;
Behzad, Mehdi
(Supervisor)
Abstract
Despite of many advantages, electro submersible pumps (ESP) have very high costs in maintenance. Since ESP usually operates in deep wells, it should be transported to the surface in order to malfunction. In addition, the state of ESP equipment cannot be determined because of unavailability of vibration measurement on the site. Thus, this equipment fails suddenly. This process costs a lot on country’s oil and water & wastewater industry. so in this thesis, at first, the potential failure modes (PFM) of ESPs are investigated, then proper methods are presented for condition monitoring. Finally, the presented methods are verified by experimental tests and wavelet analysis. The results show that...
Ultrasound Image Reconstruction using Capacitive Micromachined Ultrasonic Transducers
, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijhan (Supervisor)
Abstract
In this thesis its considered the characterization of an ultrasound wave in a medium with some obstacles. Derivation of speed of molecules and pressure of the wave is carried out in the Cartesian coordinates system. Simulation is carried out to prove the dependency of wave speed to set up parameters such as the target point (x,y,z) at which the speed value is obtained, the location of the obstacles, the amplitude of original wave emitting from the source, and the propagation speed in different layers of the medium. From the numerical results, it is apparent that the amplitude of the speed wave gets degraded as the wave travels through the medium which is a function of reflection and...
Improvements in audio classification based on sinusoidal modeling
, Article 2008 IEEE International Conference on Multimedia and Expo, ICME 2008, Hannover, 23 June 2008 through 26 June 2008 ; 2008 , Pages 1485-1488 ; 9781424425716 (ISBN) ; Ghaemmaghami, S ; Razzazi, F ; Sharif University of Technology
2008
Abstract
In this paper, a set of features is presented and evaluated based on sinusoidal modeling of audio signals. Amplitude, frequency, and phase parameters of the sinusoidal model are used and compared as input features into an audio classifier system. The performance of sinusoidal model features is evaluated for classification of audio into speech and music classes using both the Gaussian and the GMM (Gaussian Mixture Model) classifiers. Experimental results show superiority of the amplitude parameters of the sinusoidal model, which could be used for the first time for such an audio classification, as compared to the popular cepstral features. By using a set of 40 sinusoidal features, we achieved...
Considerations on the Empirical Adequacy of Jung’s Theory of Psychoanalysis
, M.Sc. Thesis Sharif University of Technology ; Hosseini Sarvary, Hassan (Supervisor)
Abstract
Carl Jung's analytical psychology is a psychoanalytic theory that has been established with the assumption of the existence of a collective and inheritable unconscious containing archetypes. The archetypes are psychic patterns that have evolved throughout human history and are inherited by human infants. Repressing these innate and universal properties can cause psychic problems for humans. Those repressed innate properties could emerge indirectly to keep the mental balance, but this may cause problems due to being out of conscious control of the individual. According to Jung's claim, remembering and accepting these repressed identities and then integrating the conscious and unconscious...
FPGA-based fault injection into synthesizable verilog HDL models
, Article 2nd IEEE International Conference on Secure System Integration and Reliability Improvement, SSIRI 2008, Yokohama, 14 July 2008 through 17 July 2008 ; 2008 , Pages 143-149 ; 9780769532660 (ISBN) ; Miremadi, S. G ; Sharif University of Technology
2008
Abstract
This paper presents an FPGA-based fault injection tool, called FITO that supports several synthesizable fault models for dependability analysis of digital systems modeled by Verilog HDL. Using the FITO, experiments can be performed in real-time with good controllability and observability. As a case study, an OpenRISC 1200 microprocessor was evaluated using an FPGA circuit. About 4000 permanent, transient, and SEU faults were injected into this microprocessor. The results show that the FITO tool is more than 79 times faster than a pure simulation-based fault injection with only 2.5% FPGA area overhead. © 2008 IEEE
ICoSim-FMS: An intelligent co-simulator for the adaptive control of complex flexible manufacturing systems
, Article Simulation Modelling Practice and Theory ; Volume 19, Issue 7 , August , 2011 , Pages 1668-1688 ; 1569190X (ISSN) ; Mahdavi, I ; Mahdavi Amiri, N ; Sharif University of Technology
2011
Abstract
We describe an intelligent co-simulator for real time production control of a complex flexible manufacturing system (CFMS) having machine and tool flexibility. The manufacturing processes associated with the CFMS are complicated with each operation being possibly done by several machining centers. The co-simulator design approach is built upon the theory of dynamic meta-model based supervisory control with the cooperation of its own embedded intelligent blocks. The system is implemented by coupling of the centralized simulation controller (CSC) and real-time simulator for enforcing dynamic strategies of shop floor control. The posteriori adaptive co-simulator is equipped with a concurrent...
Effect of intervertebral translational flexibilities on estimations of trunk muscle forces, kinematics, loads, and stability
, Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 18, Issue 16 , Sep , 2015 , Pages 1760-1767 ; 10255842 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
Due to the complexity of the human spinal motion segments, the intervertebral joints are often simulated in the musculoskeletal trunk models as pivots thus allowing no translational degrees of freedom (DOFs). This work aims to investigate, for the first time, the effect of such widely used assumption on trunk muscle forces, spinal loads, kinematics, and stability during a number of static activities. To address this, the shear deformable beam elements used in our nonlinear finite element (OFE) musculoskeletal model of the trunk were either substantially stiffened in translational directions (SFE model) or replaced by hinge joints interconnected through rotational springs (HFE model). Results...