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kafili-gavgani--ali
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Design and Implementation of an Over-Actuated Quadrotor with Rotatable Motors Axes
, M.Sc. Thesis Sharif University of Technology ; Alasty, Aria (Supervisor) ; Nejat, Hossein (Supervisor) ; Talaeizadeh, Amin (Co-Supervisor)
Abstract
Conventional multirotor UAVs are inherently underactuated, preventing independent control of all degrees of freedom and thereby limiting their ability to perform complex maneuvers and specialized missions. This thesis introduces and implements the Sharif AgRoCopter, a fully-actuated quadrotor equipped with additional actuators to tilt the rotor axes, enabling full independent control across all degrees of freedom. A comprehensive comparative analysis of various omniorientational configurations is presented, offering a roadmap for configuration selection and controller design aligned with different design objectives. A novel control strategy based on virtual control signal generation and both...
The impact of mechanical tuning on the printability of decellularized amniotic membrane bioinks for cell-laden bioprinting of soft tissue constructs
, Article Scientific Reports ; Volume 14, Issue 1 , 2024 ; 20452322 (ISSN) ; Tamjid, E ; Simchi, A ; Sharif University of Technology
2024
Abstract
Decellularized extracellular matrix (dECM) bioinks hold significant potential in the 3D bioprinting of tissue-engineered constructs (TECs). While 3D bioprinting allows for the creation of custom-designed TECs, the development of bioinks based solely on dAM, without the inclusion of supporting agents or chemical modifications, remains underexplored. In this study, we present the concentration-dependent printability and rheological properties of dAM bioinks, along with an analysis of their in vitro cellular responses. Our findings demonstrate that increasing dAM concentrations, within the range of 1 to 3% w/v, enhances the mechanical moduli of the bioinks, enabling the 3D printing of flat...
Development of injectable hydrogels based on human amniotic membrane and polyethyleneglycol-modified nanosilicates for tissue engineering applications
, Article European Polymer Journal ; Volume 179 , 2022 ; 00143057 (ISSN) ; Tamjid, E ; Niknejad, H ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Recently, decellularized amniotic membrane-derived hydrogels (DAMHs) have received significant attention for wound care, ocular surface reconstruction, and chondral healing. Despite the advantages of DAMHs for tissue engineering (TE), the loss of structural components during the decellularization process mitigates their mechanical strength and thus limits their practical application. Herein, we present a method for the surface modification of two-dimensional nanosilicates (laponite) as a rheological modifier to tailor the properties of DAMHs. Results show that after introducing nanosilicates, severe aggregation of the nanoparticles occurs, owing to the shielding effect of ions on the surface...
Development of printable nanoengineered composite hydrogels based on human amniotic membrane for wound healing application
, Article Journal of Materials Science ; Volume 58, Issue 30 , 2023 , Pages 12351-12372 ; 00222461 (ISSN) ; Tamjid, E ; Niknejad, H ; Simchi, A ; Sharif University of Technology
Springer
2023
Abstract
Recently, decellularized amniotic membranes (dAM) have attracted significant interest as a valuable source for the development of shear-thinning hydrogels and bioinks. However, the inferior rheological behavior and weak mechanical durability restrict the printability of the hydrogels and their stability after three-dimensional (3D) bioprinting. Therefore, a chemical or physical modification with biocompatible components is necessary to improve dAM-derived hydrogels’ properties. The present study proposes a strategy to fabricate printable dAM-derived hydrogels (DAMHs) supplemented with sodium alginate and Laponite nanoplatelets. Rheological experiments determined the key role of Laponite...
Development of bioinspired nanocomposite bioinks based on decellularized amniotic membrane and hydroxyethyl cellulose for skin tissue engineering
, Article Cellulose ; Volume 31, Issue 5 , 2024 , Pages 2989-3013 ; 09690239 (ISSN) ; Tamjid, E ; Niknejad, H ; Simchi, A ; Sharif University of Technology
2024
Abstract
Although hydrogels developed based on the decellularized amniotic membrane (dAM) hold great promise for tissue engineering and regenerative medicine, the development of printable bioinks faces serious limitations considering appropriate rheological behavior and shape fidelity after 3D printing. To improve the printability of dAM, we propose that hydroxyethyl cellulose (HEC) and silicate nanoplatelets (Laponite) can be used as a thickening agent and rheology modifier, respectively. It is shown that the Laponite operates as a physical crosslinking agent through reversible non-covalent interactions between nanoplatelets and the biopolymer matrix, thus improving the storage modulus of the bioink...
Concentration modulated microstructure and rheological properties of nanofibrous hydrogels derived from decellularized human amniotic membrane for 3D cell culture
, Article Journal of Materials Science: Materials in Engineering ; Volume 19, Issue 1 , 2024 ; 30048958 (ISSN) ; Tamjid, E ; Niknejad, H ; Simchi, A ; Sharif University of Technology
2024
Abstract
Decellularized amnion (dAM)-derived hydrogels have been extensively exploited for versatile medical and therapeutical applications, particularly for soft tissue engineering of skin, vascular graft, and endometrium. In contrast to polyacrylamide-based hydrogels, which have been extensively employed as a 3D cell culture platform, the cell response of dAM hydrogel is yet to be understood. In this study, we have prepared hydrogels containing different concentrations of dAM and systematically investigated their microstructural features, gelation kinetics, and rheological properties. The results show that dAM hydrogels possess a network of fibers with an average diameter of 56 ± 5 nm at 1% dAM,...
Amnion-derived hydrogels as a versatile platform for regenerative therapy: from lab to market
, Article Frontiers in Bioengineering and Biotechnology ; Volume 12 , 2024 ; 22964185 (ISSN) ; Niknejad, H ; Tamjid, E ; Simchi, A ; Sharif University of Technology
2024
Abstract
In recent years, the amnion (AM) has emerged as a versatile tool for stimulating tissue regeneration and has been of immense interest for clinical applications. AM is an abundant and cost-effective tissue source that does not face strict ethical issues for biomedical applications. The outstanding biological attributes of AM, including side-dependent angiogenesis, low immunogenicity, anti-inflammatory, anti-fibrotic, and antibacterial properties facilitate its usage for tissue engineering and regenerative medicine. However, the clinical usage of thin AM sheets is accompanied by some limitations, such as handling without folding or tearing and the necessity for sutures to keep the material...
Dynamic modeling and sliding mode control of an over-actuated quadrotor with variable hedral angle of propeller axes
, Article 2nd International Conference on Unmanned Vehicle Systems-Oman, UVS 2024 ; 2024 ; 979-835037255-7 (ISBN) ; Talaeizadeh, A ; Heidarzadeh, S ; Alasty, A ; Nejat Pishkenari, H ; Sharif University of Technology
2024
Abstract
The conventional quadrotor, characterized by four control inputs to control six degrees of freedom, is inherently under-actuated, resulting in limited independent control over pitch and roll angles. In this study, we present a configuration that incorporates four additional control inputs for manipulating the angles of the propeller axes. This addresses the previously mentioned limitations and offers additional advantages. Also, it can exhibit enhanced stability during altitude reduction by mitigating the vortex ring state. We derive the dynamic model for this system using Newthon-Euler's method. To address unmodeled dynamics, uncertainties, disturbances, and the inherent complexity of these...
Determining the Optimal Kinetic Equation for the Transesterification Process in a Batch Reactor
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Sirous (Supervisor) ; Larimi, Afsane Sadat (Supervisor)
Abstract
The aim of this project is to inventigate and synthesize CaO-based nanocatalysts with metal promoters of magnesium and lithium by wet impregnation and coprecipitation methods, which are used in the transesterification reaction of canola oil and methanol. Sections of thesis include review of before researches , synthesis of nanocatalysts, catalyst characterization tests,and investigation of reaction under optimal conditions. In wet impregnation method, nanocatalysts were made with 5% by weight of lithium-magnesium on the basis of CaO and with different weight percentages of these two elements. In the co-precipitation method , catalysts with a combined base of calcium oxide/magnesium oxide ...
Investigation of One-Pot Three-Component Reaction of Naphthalenediols with Formaldehyde and Amines under Catalyst-free Conditions
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Reza (Supervisor) ; Ziyaei Halimehjani, Azim (Supervisor)
Abstract
In this study, a catalyst-free Mannich reaction is applied for synthesis of 1,3-oxazines as an important class of biologically active compounds. In order to consider environmental application a mixture of water and ethanol is selected as a solvent for the reaction of 2,7-dihydroxynaphthalene with formaldehyde and an amine. Primary consideration of substitution effect on the reaction revealed that aniline and its derivatives with electron-donating substituent and halogens, cause higher yield. Aliphatic amines are not good substrate for this reaction with the exception of benzyl amine
3D Bioprinting of Amniotic Membrane-Based Nanocomposite for Tissue Engineering Applications: Evaluation of Rheological, Mechanical and Biological Properties
, Ph.D. Dissertation Sharif University of Technology ; Simchi, Abdolreza (Supervisor) ; Tamjid, Elnaz (Supervisor) ; Niknejad, Hassan (Co-Supervisor)
Abstract
3D bioprinting is an additive manufacturing method that facilitates the deposition of the desired cells and biomaterials at any pre-defined location. This technique also enables control over the internal structure and external dimensions of printed constructs. Among various biomaterials used as bioinks, the bioinks derived from decellularized extracellular matrixes (dECMs) have attracted significant attention due to their bioactivity and being a rich source of biochemical cues. Here in this study, the decellularized amnion membrane (dAM) has been selected as the main component of the bioink formulation because of its biocompatibility, low immunogenicity, antibacterial property, abundance,...
Technical English for mechanical engineers
, Book ; Meghdari,Ali
Sharif University Press
2014
Abstract
Local educational institutions produce in-house English for Specific Purpose (ESP) materials according to the curriculum policies designated and developed by the Ministry of Higher Education In Iran. To this end, this book aims to be used in the Iranian setting at the tertiary level for undergraduate students majoring in Mechanical Engineering. Moreover, the style of English usage in this ESP textbook is American.
Regarding the content of the textbook, it has both thematic organizations in which the topics are relevant and includes sufficient treatment of the target language areas necessary for the students. The principle organizing approach of this textbook is theme-based. In addition,...
Regarding the content of the textbook, it has both thematic organizations in which the topics are relevant and includes sufficient treatment of the target language areas necessary for the students. The principle organizing approach of this textbook is theme-based. In addition,...
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...
Design and Construction of a Soft Actuated Exoskeleton for Hand Rehabilitation of Stroke Patients
, M.Sc. Thesis Sharif University of Technology ; Ghafari, Ali (Supervisor) ; Meghdari, Ali (Supervisor)
Abstract
The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to...
Silica chloride/wet SiO2 as a novel heterogeneous system for the deprotection of acetals under mild conditions [electronic resource]
, Article Phosphorus, Sulfur, and Silicon and the Related Elements ; Volume 178:2667-2670, Issue 12, 2003 ; Pourjavadi, Ali ; Zolfigol, Mohammad Ali ; Bamoniri, Abdolhamid
Abstract
A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition
Earthquake Branch
, M.Sc. Thesis Sharif University of Technology ; Bakhshi, Ali (Supervisor)
Abstract
In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have...
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have...
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
Comparison between Performance of Stone Columns and RAPs from the Bearing Capacity and Settlement Reduction Viewpoints
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
Out of several ground improvement techniques available, stone columns have been widely used. This technique has been successfully applied to increase the bearing capacity and to reduce the settlement for foundation of structures like liquid storage tanks, earthen embankments, raft foundations, etc., where a relatively large settlement is permissible. This technique has, generally, been proven successful in increasing the stiffness of weak soils, upgrading their safe bearing capacity, and reducing their total and differential settlements, as well as speeding up their consolidation process. The beneficial effects of stone column installation in weak deposits is manifested in the form of...
Performance of Partially Filled Mini-Channels with Porous Media
, M.Sc. Thesis Sharif University of Technology ; Nouri, Ali (Supervisor) ; Moosavi, Ali (Co-Advisor)
Abstract
Laminar forced convection flow through a channel partially filled with a porous material was numerically studied in this thesis. The Navier-Stokes and Brinkman-Forchheimer equations were used to model the fluid flow in the free and porous regions, respectively. Coupling of the pressure and velocity fields was resolved using the SIMPLEC algorithm. The local thermal equilibrium was adopted in the energy equation. The effects of the thermal conductivity ratio, Darcy number, porosity, Reynolds number and height of the porous insert on velocity and temperature field were investigated. The results show that the flow behavior and its associated heat transfer are susceptible to the variation of the...