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Total 31 records
Device on a Chip, in Order to Control and Separation of Circulating Tumor Cells
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Khodaygan, Saeed (Supervisor)
Abstract
The process of separating cells from a laboratory sample, is a crucial step in biotechnology and medical science. Cells separation is important for various reasons, including the identification and treatment of diseases, as an example, separation of Circulating Tumor Cells (CTCs) from patient blood sample. CTCs are cells that shed from a tumor and diffuse into blood vessels. These cells are the starters of metastasis, the process in which cancer spreads in body, and are main reason of deaths caused by cancer. Extremely low percentages of target cells in the blood, clarify the importance of highly accurate and sensitive separation. Currently, conventional separation methods are of macro-order...
Optimization of Scan Algorithms in Selective Laser Sintering
, M.Sc. Thesis Sharif University of Technology ; Movahhedi, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Supervisor)
Abstract
One of the most important manufacturing methods using technologies AM, is the SLS method. This method because it would significantly reduce the construction time is the ability to build a variety of materials, is pervasive. The SLS devices input is part CAD file which is then part layered, a layer of powder is poured on the bed. Each layer is defined contour on the part and then scanned by laser inner layer is hatched by laser. Scanning algorithms and hatching in the SLS is an important part of building that has an impact on properties part and a lot of research has been done about it. synthetic scan algorithms presented in this study. The purpose of this algorithm is that part warpage and...
Optimal Design of the High Speed Spindle Bearings to Reduce Non Repeatable Run Out
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor) ; Movahhedy, Mohammad Reza (Co-Advisor)
Abstract
Creating synchronous conditions of precision and speed in rotating systems is a requirement for the design of these systems. The requirement to create these conditions is essential in various applications, such as machine tools and computer equipment. One of the main sources of error in the motion of the high speed spindles is the occurrence of non-repetitive runouts. The presence of non-repetitive runouts at high speeds greatly affects the accuracy of the rotating motion of rotating systems and reducing its effects is always considered in the design of high speed rotary systems. Usually, one of the most important factors in the occurrence of non-repetitive runouts is related to spindle...
Reliability Based Robust Design Optimization of Mechanical Systems with Uncertain Parameters Using Bayesian Inference
,
M.Sc. Thesis
Sharif University of Technology
;
Khodaygan, Saeed
(Supervisor)
;
Asempour, Ahmad
(Supervisor)
Abstract
This world’s commercial and competitive space force’s designers and manufactures to produce and supply products with high quality and low price at desirable level of reliability. On the other hand, during the design and production process, Engineers are always faced with uncertainty. Essentially, uncertainties can be divided into two categories: aleatory and epistemic. Aleatory uncertainties are due to changes in design conditions, material properties, physical dimensions of components and operating conditions. This kind of uncertainty will not be reduced during the life.on the otherhand, Epistemic uncertainties that are due to lack of knowledge about physical nature of systems can be...
Finite Element Simulation of Machining Chatter in Turning and Milling with Orthogonal Geometry, Taking into Account of Two-Dimensional Machine Tool Dynamics
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Co-Advisor)
Abstract
Chatter vibration is a major obstacle in high quality machining. This undesirable vibration decreases the production rate, surface quality, tool life and machine tool life. In the last few decades, a lot of models have been presented to predict chatter. Most of the models, whether linear or nonlinear, have focused on modeling of machine tool dynamics and either disregard the effective parameters of chip formation process or apply some of these parameters through simplified equations. In this research, a finite element simulation of chip formation is combined with the dynamics of machine tool to investigate chatter and its effective factors. The proposed approach, unlike common mathematical...
Tolerance Design of Mechanical Systems based on Reliability Modeling under Bayesian Inference
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor) ; Assempour, Ahmad (Supervisor)
Abstract
Mechanical production centers are seeking to produce the highest quality products at the lowest cost. Intrinsic processes of manufacturing are not precise processes, and factors such as tool wear, tool vibration and fixation, fixing defects, and other factors that occur during production, make the pieces deviate from the designer's desirable geometry. Usually, due to deviations of parts from their size, their dimensional and geometric characteristics change. Because the components are rarely just a part, often in the majority of parts of the assembly, the operation of the set may be impaired due to the accumulation of changes. Errors that are usually caused during component assembly due to...
Tolerance Design of Mechanical Parts Considering Degradation and Quality Loss in Manufacturing Process and Operating Conditions
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor) ; Asempour, Ahmad (Supervisor)
Abstract
The tolerance stack-up in mechanical assemblies is closely related to the quality of finished products and to the costs of production. In practice, choosing a large tolerance range will result in performance reduction. On the other hand, with small tolerances considered, production costs will increase. Tolerance allocation is a useful tool to control the dimensional and geometric variables of the product, so design engineers can control the final product quality level, production cost, and other variables. The proposed method for tolerance design considers the effects of degradation and quality loss over time and allocates tolerances so that, the functional key characteristic satisfies, as...
Automatic System Identification Algorithm Including Uncertainty Estimation based on Operational Modal Analysis
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor) ; Movahedi, Mohammad Reza (Supervisor)
Abstract
Modal analysis is very important in determining the physical properties of structures and mechanisms. This field is divided into two general parts: Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA). In the operational modal analysis, there are more challenges for the analyst due to the lack of inputs to identify the system. Many of the mechanical structures can not be analyzed experimentally and under specific loadings, but should be identified under actual operating conditions and in situations where the inputs of the system are not measurable. For this purpose, a modal analysis method called "Random Sub-Space Identification" (SSI) is intoduced, which uses only output...
Experimental Study and Optimization of Laser Assisted Machining of Particle Reinforced Aluminum Matrix Composite
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Co-Supervisor)
Abstract
In this thesis, the process of laser assisted machining (LAM) of metal matrix composites (MMC) is experimentally studied. The effects of process parameters (cutting speed, feed rate and depth of cut), laser parameters (laser power, laser frequency and laser beam angle), and the percentage of reinforcing particles on the tool wear and the surface roughness are investigated. Furthermore, the effects of these parameters on the built-up edge (BUE), chip shape, and workpiece temperature are explored.The experiments were performed using uncoated tungsten carbide and PCD tools under dry conditions. In order to analyze the sensitivity of the process parameters, the Plackett-Burman method was used...
Modeling Geometrical Deviations and Tolerance Analysis Based on NURBS and Isogeometric Method
, Ph.D. Dissertation Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Supervisor)
Abstract
Non-uniform rational B-spline (NURBS) curves and surfaces are one of the most powerful tools of computer-aided design, which are able to model both free-form and analytic shapes. In this dissertation, the idea of using NURBS curves as a tool for modeling geometrical deviations and tolerance analysis of mechanical assemblies is presented and evaluated. In the first step the effect of changing the defining variables of NURBS on shape of the curve is investigated. After that, by establishing a relationship between profile tolerance and random NURBS curves, two concepts of tolerance zone width and correlation function are introduced, and a method based on regression algorithms and covariance of...
Numerical Modelling and Experimental Validation of Nano Colloid Droplet Formation in the Electrohydrodynamic 3D Printer
, Ph.D. Dissertation Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Supervisor) ; Simchi, Abdolreza (Co-Supervisor) ; Mofrad, Mohammad Reza (Co-Supervisor)
Abstract
The electrohydrodynamic (EHD) 3D printing technology is an Additive Manufacturing (AM) method that can be used in the manufacture of submicron-size structures. Due to the multiphysics dynamics and the multiphase nature of the microdroplet formation in the EHD printers, modeling of this phenomenon is complicated. In this thesis, the formation of a droplet in an EHD printer—under a pulsed electrical field—is simulated using a new numerical model which couples the fluid flow, the electric field distribution and the movement of the electric charges under dynamic and transient conditions. The level-set method is applied to the entire multiphysics domain in order to study the formation of the...