3Dimentional Numerical Modeling of Air Particle Flow in a Cleanroom

, M.Sc. Thesis Sharif University of Technology Molaei Manesh, Gholam Reza (Author) ; Saeedi, Mohammad Hassan (Supervisor)

Abstract

Nowadays, cleanrooms have a growing application in a broad range of industries, e.g. pharmacy, aerospace, nuclear energy and electronics. So, it seems that numerical modeling of airflow in such spaces becomes more essential. As computational fluid dynamics has become a powerful tool for indoor airflow studies, in this research, influence of effective parameters on the flow and concentration distribution in cleanrooms has been investigated by the use of CFD. To do so, aerosol flow in a 3-D cleanroom has been numerically modeled by Fluent 6.3, using Euler-Euler approach and standard k- turbulence model. Comparison between numerical results and experimental data shows a considerably good...

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 Selk Ghafari, A. (Ali) ; 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...

Modeling, Identification and Velocity Estimation of Planar Hybrid Microrobot

, M.Sc. Thesis Sharif University of Technology Nojoumian, Mohammad Ali (Author) ; 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...

Super Heavy Crude Oil Refinery Project Feasibility Study

, M.Sc. Thesis Sharif University of Technology Mansouri, Gholam Reza (Author) ; 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...

Robust Control of Regenerative Chatter in Orthogonal Cutting Process with Spindle Speed and Feed Rate Variation

, M.Sc. Thesis Sharif University of Technology Haji Hajikolaei, Kambiz (Author) ; 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...

Design and Construction of a Bent Crystal Spectrometer for Studying Soft X-Rays of Sharif Plasma Focus

, M.Sc. Thesis Sharif University of Technology Hosseinzadeh, Abdolhadi (Author) ; 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...

Dynamic Analysis of an Exoskeletal System to Assist a Paraplegic Motion

, Ph.D. Dissertation Sharif University of Technology Selk Ghafari, Ali (Author) ; 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 Torabi, Payman (Author) ; 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...

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 Sayyar Masoule, Zahra (Author) ; 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) Pourjavadi, A. (Ali) ; 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 Pourjavadi, A. (Ali) ; 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 Alidoust, Ali (Author) ; 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 Sharifi, Amin (Author) ; 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 Ghorashi, Mir Siavash (Author) ; 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...

The Relationship between Dividend Policy and Stock Price Volatility

, M.Sc. Thesis Sharif University of Technology Baghbani, Masood (Author) ; 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...

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 Dashtian, Hassan (Author) ; 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) Ezzatian, R ; 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...

Immobilized manganese porphyrin on functionalized magnetic nanoparticles via axial ligation: Efficient and recyclable nanocatalyst for oxidation reactions

, Article Journal of Coordination Chemistry ; Volume 68, Issue 13 , 2015 , Pages 2347-2360 ; 00958972 (ISSN) Bagherzadeh, M ; Mortazavi Manesh, A ; Sharif University of Technology

Taylor and Francis Ltd 2015

Abstract

Magnetic nanoparticles (MNPs), Fe3O4@SiO2, have been prepared and functionalized by 3-(chloropropyl)trimethoxysilane and then by imidazole to synthesize Fe3O4@SiO2-Im. The functionalized Fe3O4 nanoparticles were used as a support to anchor manganese porphyrin via axial ligation. The prepared catalyst was characterized by elemental analysis, FT-IR spectroscopy, X-ray powder diffraction, UV-vis spectroscopy, and scanning electron microscopy. Application of immobilized manganese porphyrin as a heterogeneous catalyst in oxidation of alkenes and sulfides was explored. To find suitable reaction conditions,...

Nanoparticle supported, magnetically separable manganese porphyrin as an efficient retrievable nanocatalyst in hydrocarbon oxidation reactions

, Article RSC Advances ; Volume 6, Issue 47 , 2016 , Pages 41551-41560 ; 20462069 (ISSN) Bagherzadeh, M ; Mortazavi Manesh, A ; Sharif University of Technology

Royal Society of Chemistry 2016

Abstract

A manganese porphyrin, meso-tetrakis(pentafluorophenyl)porphyrinato manganese(iii) acetate, Mn(TPFPP)OAc, was immobilized on silica-coated magnetic Fe3O4 nanoparticles functionalized with 3-aminopropyltriethoxysilane (APTS) through the amino propyl linkage using a grafting process in toluene solvent. This enabled the covalent immobilization of Mn(iii) porphyrin via an aromatic nucleophilic substitution reaction, to afford the Fe3O4@SiO2-NH2@MnPor catalyst. The resulting nanoparticles were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectroscopy, UV-Vis spectroscopy, elemental analysis (CHN), atomic absorption spectroscopy (AAS), and vibrating...

Synthesis and characterization of molybdenum (VI) complex immobilized on polymeric Schiff base-coated magnetic nanoparticles as an efficient and retrievable nanocatalyst in olefin epoxidation reactions

, Article Applied Organometallic Chemistry ; Volume 34, Issue 3 , 2020 Mortazavi Manesh, A ; Bagherzadeh, M ; Sharif University of Technology

John Wiley and Sons Ltd 2020

Abstract

In this study, a new polymeric functionalized magnetic nanocatalyst containing a molybdenum Schiff base complex was prepared using a few consecutive steps. Poly (methylacrylate)-coated magnetic nanoparticles were synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups with hydrazine. Polymeric functionalization efficiently provides the advantage that more catalytic units can be grafted on the surface of magnetic nanoparticles. The functionalization process was continued with salicylaldehyde which introduced Schiff base groups on to the surface of the polymeric support. In the final step, the desired...