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Modeling, Identification and Velocity Estimation of Planar Hybrid Microrobot
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholam Reza (Supervisor)
Abstract
Microrobots are the robots which manufactured or operated in micro dimentions. High accuracy, compatibility with harsh situations and caring or assembling in micro dimensions are the most important advantages of these robots. Manufacturing new microrobots with higher speed or increasing the velocity of existed microrobots is the discussion of these days.An A-shape microrobot designed and manufacturared before. The goal of this thesis is to model, identify the friction and observe the velocity of the A-shape microrobot. In low speeds both legs of microrobots are on the ground; it walks with the stick-slip motion principle. Increasing the velocity of the microrobot causes separation of one or...
Feedback control of the neuro-musculoskeletal system in a forward dynamics simulation of stair locomotion [electronic resource]
, Article Proc. of IMechE Part H: Journal of Engineering in Medicine ; 2009, Vol. 223, No. 6, pp. 663-675 Journal of NeuroEngineering and Rehabilitation ; Volume 11, Issue 1, 30 April 2014, Article number 78 ; Meghdari, Ali ; Vossough, Gholam Reza ; Sharif University of Technology
Abstract
The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of...
Robust Control of Regenerative Chatter in Orthogonal Cutting Process with Spindle Speed and Feed Rate Variation
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholam Reza (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
During the turning operation, the interaction of the metal cutting process and machine tool causes a dynamic instability called self-excited vibration or chatter. Limited productivity rate, decrease in tool life, poor surface quality and noisy workplace are some adverse effects of the chatter vibration. Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this thesis, two control strategies are developed to suppress chatter vibration in turning process including a worn tool. A single degree of freedom model of the turning process including tool wear is briefly described. In the first stage, a sinusoidal spindle speed...
Dynamic Analysis of an Exoskeletal System to Assist a Paraplegic Motion
, Ph.D. Dissertation Sharif University of Technology ; Meghdari, Ali (Supervisor) ; Vossoughi, Gholam Reza (Co-Advisor)
Abstract
This research focuses on the dynamic analysis of an exoskeletal system to assist a paraplegic motion. Research in powered human exoskeletons began in the late 1960s, almost in parallel between the numbers of research groups for different applications. The main challenges for the recent work in exoskeletons were focused on the design and demonstration of an initial prototype. To this point, the reported advantages of the autonomous exoskeleton systems are largely anecdotal. Indeed, there is a marked lack of published quantitative performance results for exoskeleton devices that reportedly improve human locomotion. Considering this, there are many design challenges remained that may lead to...
Bilateral Control of a Telesurgical Workstation with Haptic Feedback of an open Surgery
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholam Reza (Supervisor) ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
The introduction of Minimally Invasive Surgery (MIS) has deeply influenced modern surgery. Despite all the advantages for the patient, this method produces some limitations for the surgeon. Limitations such as reducing degrees of freedom resulting in the loss of dexterity, depriving surgeons of the depth perception and sense of touch lead to human errors due to fatigue and intense mental activity. Overcoming these limitations is the reason for robots entering the operating rooms. In this research a robot-assisted surgery system including two 5-DOF robots is utilized. The goal of this research is to model and simulate this system and also to design a bilateral controller to provide haptic...
Super Heavy Crude Oil Refinery Project Feasibility Study
, M.Sc. Thesis Sharif University of Technology ; Safaeih, Mohammad Reza (Supervisor)
Abstract
The market demand of super heavy crude oil is very low due to its determinative both physical and chemical properties. Unfortunately existing refineries in Iran are not capable to refine this kind of crude oil. Marketing issues besides great price difference with other crude oil types leads us to find economical solution for optimal use of this national possession. About 70 percent of super heavy crude oil produced from Soroush and Norouz oil fields is un-refineable materials and to refine this heavy crude oil to refinery products like gasoline or gas oil a refinery with RFCC ( Residual Fluid Catalitic Cracking) technology must be made. Super high Technology and very heavy capital cost...
Design and Construction of a Bent Crystal Spectrometer for Studying Soft X-Rays of Sharif Plasma Focus
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Etaati, Gholam Reza (Supervisor)
Abstract
A soft X-ray spectrometer based on Johann's method and an embedded curved crystal is designed and fabricated for Sharif University of Technology's Plasma Focus (SUT-PF) in this project. Focusing rays with the same wavelength at a point to increase the ray intensity is the reason of choosing the cylindrical curved crystal spectrometer since its performance is inspired to the Bragg's law.The optimal conditions for SUT-PF (pressure and voltage) is adjusted and examined by photodiode detector and the camera pinhole before spectroscopy experiments. The diameter of generated hot spots is measured as 80 microns in the optimal condition.The recorded spectral lines on the radiography film and the...
An Investigation of the Reliability and Validity of Peer-, Self-, and Teacher Assessment in EFL Learners’ Written and Oral Production
, M.Sc. Thesis Sharif University of Technology ; Salehi, Mohammad (Supervisor) ; Abbasian, Gholam Reza (Co-Advisor)
Abstract
Traditional assumptions about assessment and learning have been challenged in higher education. Alternative types of assessment have been introduced to align to the students’ learning aims. Although, the growing body of literature of alternative types of assessment such as peer-assessment and self-assessment shed light on the advantages and benefits of embedding assessment in classroom activities, there is not absolute agreement on the consistency and accuracy of these types of assessment. To this aim, this study attempted to investigate the reliability and validity of self-assessment and peer-assessment of Iranian EFL learners’ written and oral production. The data was obtained from 32...
Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions [electronic resource]
, Article Journal of Chemical Research ; Volume 2002, Number 8, 1 August 2002, pp. 378-380(3) ; Bagheri Marandi, Gholam
Abstract
Free Content Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions
Selective preparation of fluorescent 1,8-naphthalimides using acidic alumina under microwave irradiation [electronic resource]
, Article Journal of Chemical Research ; 01/2001; 2001(11):485-487 ; Bagheri Marandi, Gholam
Abstract
7H-benzimidazo[2,1-a]benz[de]isoquinolin-7-one compounds were prepared in a selective manner by reaction between o-phenylenediamines and appropriate 1,8-naphthalenedicarboxylic anhydrides using acidic alumina under microwave irradiation
Unsupervised Persian Keyword Extraction Using Exemplar Terms
, M.Sc. Thesis Sharif University of Technology ; Sameti, Hossein (Supervisor) ; Ghasem Sani, Gholam Reza (Co-Advisor)
Abstract
Keywords or keyphrases are of importance as the smallest unit of representing the meaning of a text. Automated Keyword Extraction (AKE), as one of the natural language processing tasks is used in various applications such as searching, indexing and information retrieval. Keywords of scientific articles are basically specified manually by their authors, whereas most of the information available on the internet lack such keywords. In this research, we endeavor to automatically extract keywords of a set of Persian paper abstracts using an unsupervised machine learning method. The method used is to extract a set of candidate phrases from the text, and to cluster the document words to find a set...
Experimental and Numerical Study of Low Fatigue Cycle Behavior of Magnesium-Lithium Alloy
, M.Sc. Thesis Sharif University of Technology ; Farrahi, Gholam Hossein (Supervisor) ; Kashyzadeh, Kazem Reza (Co-Supervisor)
Abstract
Application of light metals such as Magnesium alloys due to proper mechanical behavior is increasing in industries such as automotive, electronics and so on. In this project, ingot of Mg-9Li-1Zn alloy with 10 mm thickness were produced by casting, then hot rolled at 300oC to reach 2mm thickness. Annealing at 350oC for 3 hours resulted homogenous properties in the final sheet.Study of monotonic and cyclic behavior of Mg-Li alloy by experiments and FE simulation was the goal of this project. Experimental monotonic and cyclic test were carried out in order to obtain the hysteresis loops and cyclic stress-strain curve. The Chaboche constant were extracted from the experimental test and used to...
Experimental and Numerical Study of Multi-track Laser Cladding to Evaluate Effects of Residual Stress on Fatigue Life
, Ph.D. Dissertation Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Farrahi, Gholam Hossein (Supervisor) ; Shodja Razavi, Reza (Co-Supervisor)
Abstract
Laser cladding is a processing technique of layer-by-layer material deposition which is widely used to repair important components. However, tensile residual stresses generated in this process may result in detrimental effects such as crack, undesirable deformation and reduced fatigue life. A thermo-mechanical finite element model is developed to accurately predict residual stresses of the multiple beads laser cladding process with incorporating the cyclic plasticity into the analysis by utilizing the nonlinear kinematic hardening behavior. FE results are presented for Inconel 718, a material for which the laser cladding process is widely used. The FE results are compared with those of...
Photo-degradation of organic dye by zinc oxide nanosystems with special defect structure: Effect of the morphology and annealing temperature [electronic resource]
, Article Journal of Applied Catalysis A: General ; 22 February 2014, Volume 472, Pages 198–204 ; Simchi, A. (Abdolreza) ; Ghanbari, Faegheh ; Vossoughi, M ; Sharif University of Technology
Abstract
The fabrication of strong photocatalysts applied to the degradation of organic pollutants is necessary in environmental applications. In a single-stage method, acetate precursor and poly vinyl pyrolydine are used to produce ZnO nanostructures with various morphologies in annealing temperatures ranging from 300 to 900 °C. The physical properties of the prepared nanostructures were characterized by SEM, TEM, XRD, BET, DRS, CHN analysis and PL spectroscopy. The SEM images exhibit a variety of the as-prepared hexagonal zinc oxides including wires, rods, particles and porous network of welded particles of ZnO nanoparticles. The results of the photocatalytic degradation of methylene blue as an...
The Relationship between Dividend Policy and Stock Price Volatility
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholam Reza (Supervisor) ; Abdoh Tabrizi, Hossein (Supervisor)
Abstract
The objective of this study is to explore the relationship between the stock price volatility and dividend policy (dividend yield and dividend payout ratio) for the Iranian stock market. According to the studies of Baskin (1989) and Allen and Rachim (1996), the fixed effect and random effect regression models are applied in this research. The sample of data is composed of 200 public firms which are listed on the Tehran Stock Exchange (TSE) and paid dividends continuously from 2010 to 2020. The results indicate that the dividend policy has a significantly negative relationship with the stock price volatility. In addition, the Size of the company is negatively related to the stock price...
Design and Prototyping and Experimental Analysis of a Foot with Toe Joint for Exoskeletons
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Golam Reza (Supervisor)
Abstract
One of the recent studies in the field of humanoid robots is to achieve a robot gait close to the human-like gait. Therefore, using the foot equipped with passive or active toe joint is developed in case of robots. The results of several studies show that the segmented foot with a toe joint has several advantages compared to the rigid foot in: walking speed, range of joint angle and ability to kneel and climb higher steps. Both passive and active toe joints of humanoid robots are developed. Advantages of the passive toe joint is obvious; in terms of design, it is more simple and light. Moreover, in normal gait, when the robot is equipped with passive toe joint, body inertial causes an...
Analysis of Well log Data Using Detrended Fluctuation Analysis and its Comparison with Other Methods (Multifractal Analysis of Well Log Data)
, M.Sc. Thesis Sharif University of Technology ; Sahimi, Mohammad (Supervisor) ; Massihi, Mohsen (Supervisor) ; Jafari, Gholam Reza (Supervisor)
Abstract
One of the main challenges in characterization and simulation of larg scale porous media is spatial heterogeneity and variability of porous media properties such as porosity, density, and lithology at different scales. These information can be achieved at different scale from coring, well logging or seismic data. Well logs are an efficient way to obtain rock and fluid properties of geological patterns specially water resources and hydrocarbon reservoirs. One of the characteristics of geophysical well logs is their complex behavior which seems to imply a multifractal nature.In this study we investigate multifractality and presence of long range correlations in petrophysical well log data such...
Effect of C/N ratio on the phytoremediation of crude oil contaminated soils by puccinellia distance
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 27, Issue 3 , September and October , 2008 , Pages 77-85 ; 10219986 (ISSN) ; Voussoughi, M ; Yaghmaei, S ; Abedi Koupai, J ; Borghaei, M ; Gholam Reza, P ; Sharif University of Technology
2008
Abstract
Petroleum contamination of soil is a serious problem throughout the oil producer countries. Vegetation may play an important role in the biodegradation of toxic organic chemicals in soil. For petroleum compounds, the presence of rhizosphere micro flora may accelerate biodegradation of the contaminants. In a greenhouse study, petroleum contaminated soil were treated using phytoremediation . The C/N ratios and microbial populations were assessed in the beginning and the end of trials. The results showed that Puccinellia distance could tolerate the harsh condition of the soils. As MPN increases, C/N ratios decrease among trials. N, as a nutrient, had effects on both microbial populations and...
Extended Nonlinear Modeling and Stability Analysis of the Peripheral Milling Process
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Gholamreza (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
In this thesis, an extended nonlinear model of peripheral milling process (2D) is presented. For the first time, cutting forces are described through a complete third order polynomial function of the axial depth of cut. Also, cubic nonlinearity is considered for the structural stiffness as a function of tool tip displacement. To complete the model, process damping and tool wear effects are also considered. A set of experiments including modal tests to determine natural frequencies and structural damping ratios; and also cutting force measurements at different feed rates to determine nonlinear cutting force coefficients, are carried out. Also, measurement of critical axial depth of cut at...
Investigation of Application of Nano-Photocatalytic Degradation for Industrial Wastewater Treatmen
, M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza (Supervisor) ; Vossoughi, Manouchehr (Supervisor)
Abstract
The main objective of this project is the deposition of photo-catalysts on cement and concrete blocks with an emphasis on commercialization. We started with an extensive study of common methods introduced in previous literature, and conclude with a number of suggestions for industrialization. First, slurry and sol-gel deposition of the photo-catalysts on blocks of type 2 commercial cement which is one of the most used materials in construction of buildings and waste-water treatment plants has been examined to reach a method of sample formation. Due to the simplicity of common methods and low quality of formed samples (less than 5 percent aging efficiency), the obtained experience was used to...