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ghoreishi--mohammad-navid
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Design and Modeling of an Isolator System for Reducing Transmitted Vibration Levels in Space System
, M.Sc. Thesis Sharif University of Technology ; Saadat Foumani, Mahmoud (Supervisor) ; Ghoreishi, Mohammad Navid (Supervisor)
Abstract
Vibration control is one of the most critical aspects of designing space structures, as it can significantly impact the performance and operational lifespan of satellites. The launch phase is the most sensitive and critical stage in the satellite mission lifecycle, as intense vibrations are generated and transmitted to the satellite during this phase. To mitigate the severity of these transmitted vibrations, vibration isolators are employed. The objective of this study is to design and model a vibration isolator to control the vibrations transmitted from the launcher to the satellite during launch. To achieve this, an extensive investigation into vibration isolators used in the space...
A Data-Driven Framework Based on Credit Risk Management for Improving the Performance of Peer-To-Peer Lending Platforms
, M.Sc. Thesis Sharif University of Technology ; Eshghi, Kourosh (Supervisor)
Abstract
Peoples need financial resources to improve their quality of life, and companies need them to progress and increase their comparative advantage. Borrowing is one of the most popular methods of financing. Peer-to-peer lending, also known as "marketplace" or "social" lending, is a novel form of intermediation that expunges the role of financial institutions (like banks) as an intermediary and allows entities (individuals or businesses) to raise loans directly from other entities. This lending platform can provide better quality services to borrowers (by quickly providing a simple loan application process through a transparent and flexible portal) and lenders (by managing their funding and live...
Dynamic Simulation of Divided Wall Columns and Investigating Their Control Strategies
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor) ; Vafa, Ehsan (Supervisor)
Abstract
Because of lower energy consumption and lower capital cost, divided wall columns attracted wide attention. The main challenge of these units is their controllability. In this thesis dynamic simulation and control of a divided wall column is investigated and an adaptive model predictive controller has been used for control purpose. For dynamic simulation the Aspen Dynamics software and for applying control strategy the MATLAB software have been utilized. The model used for model predictive controller has been obtained by using open loop responses of the system. The main advantage of presented work over the existing ones is using the input-output transfer function of the system model instead...
Effect of Obesity on Spinal Loads during Various Activities: A Combined in Vivo-Modeling Approach
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor)
Abstract
Obesity is a worldwide growing health challenge affecting ~30% of the world's population. Increased rate of disc degeneration and herniation, low back pain and surgery has been reported in obese individuals. Although obesity-related low back diseases have multifactorial etiology, presumably greater mechanical loads on the spine of heavier individuals during their daily activities may be considered as a risk factor. Likely larger trunk muscle sizes, disc sizes and thus passive stiffness in heavier individuals may however partly or fully offset the effect of their additional body weight on the spinal loads. In absence of in vivo approaches, the present study aims to construct subject-specific...
Measurement, Analysis and Reduction Methods of Ship Vibration
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Ghoreishi, Reza (Supervisor)
Abstract
This thesis addresses the main stages of ship vibration analysis and introduces applied strategies for vibration reduction of an existing ship. First, the basic theory of ship vibration is considered and the main sources of ship vibration are enumerated. Then, the manner and the steps of vibration measurement on ship structure are presented and a summary of vibration measurement guidelines is mentioned. Afterward, the procedure how to analyze the measured data of ship vibration is outlined and a comparison between the measured data and standard limits for vibration level considering structural vibration, machinery vibration and human comfort is done. Next, human response to vibration and the...
Effect of Obesity on Spinal Loads during Various Activities: A Combined in Vivo-Modeling Approach
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Supervisor)
Abstract
Obesity is a worldwide growing health challenge affecting ~30% of the world's population. Increased rate of disc degeneration and herniation, low back pain and surgery has been reported in obese individuals. Although obesity-related low back diseases have multifactorial etiology, presumably greater mechanical loads on the spine of heavier individuals during their daily activities may be considered as a risk factor. Likely larger trunk muscle sizes, disc sizes and thus passive stiffness in heavier individuals may however partly or fully offset the effect of their additional body weight on the spinal loads. In absence of in vivo approaches, the present study aims to construct subject-specific...
The Effects of Vibrations Transferred to Vehicle Occupants on Spinal Loads as Function of Pelvic-lumbar Orientation, Posture, Seat Specifications and Seat Back Inclination Using FEM
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Supervisor)
Abstract
Due to adverse health problems with lumbar spine among professional drivers associated with exposure to whole body vibration (WBV), studying the effect of vibrations and parameters influencing WBV is of great importance. This study aims to simulate whole body vibration for a ground vehicle occupant and calculate loads that lumbar spine tolerate during harmonic sinusoidal vibrations. Moreover, this study determines the effect of lumbar spine angle, seat specifications (angles and materials), and vibration frequency on the results. To this end, a detailed viscoelastic lumbar spine (L1-S1) has been modeled using FE method which has been replaced with the simplified spine model in HYBRID III...
Development of an Evolutionary Algorithm Based on Surrogate Models to be used in Multi-disciplinary Design Optimization of a Flying Vehicle
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
In this research, multi-disciplinary design optimization (MDO) of a flying vehicle has been done based on the flight simulation. A meta-heuristic algorithm called Multi-objective Adaptive Real-coded Memetic Algorithm (MARCOMA) has been used for optimization. Since solving a MDO problem is a time consuming process, a RBF neural network has been used in the optimization algorithm as a surrogate model. The new algorithm, called MARCOMA+NN, has been tested with some standard benchmarks. MDO problem has six disciplines consists structure, aerodynamic, propulsion, guidance, control, and fire control. The MDO problem has 31 design variables and two objective functions. The objective functions are...
A Model for Optimizing Railway Alignment Problem Considering Bridge and Tunnel Cost and Using Transional Curves
, M.Sc. Thesis Sharif University of Technology ; Shafahi, Yusof (Supervisor)
Abstract
Due to large range searches (there are various alignments between two points) as well as the complex and non-linear cost functions and a variety of geometric constraints, the problem of optimal railway alignment is known as a difficult problem. For this reason, choosing an alignment between two points is usually done based on a limited number of alignments put forward by experts. In recent years, the study of the railway alignment optimization raised again due to the importance of optimization and introduction of various algorithms and their progress in solving various problems. It is expected that applying metaheuristic optimization algorithms, such as methods based on Swarm intelligence...
A Detailed Nonlinear Finite Element Model of the L4-L5 Motion Segment to Predcit Spinal Loads during in Vivo Activities
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Supervisor)
Abstract
Several geometrically-detailed passive finite element (FE) models of the lumbar spine have been developed and validated under in vitro loading conditions. As these models are devoid of muscles, they are either not used to simulate in vivo activities or muscle forces are modeled by a hypothetical compressive follower load (FL). A number of symmetric and asymmetric static tasks were first simulated using a validated musculoskeletal model of the thoracolumbar spine to predict trunk muscle forces. The predicted muscle forces along with the gravity loading were then applied to a passive FE model of the L4-L5 motion segment (developed and validated here) to estimate load sharing among the disc,...
Design of a Novel Cable Driven Robotic System for Simulation of in vivo Loading of Cadaveric Lumbar Spine with Robustness-adaptive Controller for in vitro Spine Testing
, M.Sc. Thesis Sharif University of Technology ; Parnianpour, Mohammad (Supervisor) ; Arjmand, Navid (Supervisor)
Abstract
In this project we plan to propose a mechanism for controlling the profile of vertebra displacment and intera-discal pressure in in-vitro tests. Spineis the one of the most important members of the human musculoskeletal system. Health and stability of the spine help the people to moves on two legs. So any problems with this organ, causing movement problems and pain. For the treatment of spinal diseases, several methods such as surgery, insertion of implants and stabilizing were used. To ensure the accuracy of these methods, laboratory examination is essential. One of the ways to test these interventions, the implementation of in vitro tests on samples obtained from the bodies of the spine....
The Laguerre collocation method for third kind integral equations on unbounded domains
, Article Computational Methods in Applied Mathematics ; Volume 16, Issue 2 , 2016 , Pages 245-256 ; 16094840 (ISSN) ; Farahbakhsh Tooli, E ; Sharif University of Technology
2016
Abstract
The aim of this paper is to approximate the solution of a class of integral equations of the third kind on an unbounded domain. For computing such approximation, the collocation method based on the generalized Laguerre abscissas is considered. In this method, the unknown function is interpolated at the nodal points {ti}i=1 n+1, where {t i } i=1 n are the zeros of generalized Laguerre polynomials and t n+1 =4. Then, the given equation is transformed to the Fredholm integral equation of the second kind. In the sequel, according to the integration interval, we apply the Gauss-Laguerre collocation method on the interval [0,∞) by using the given nodal points. Therefore, the solution of the third...
Effects of Low Back Pain and Posterior Lumbar Surgery on Pattern of Muscle Activities, Trunk Strength and Spinal Stability
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Arjmand, Navid (Co-Advisor)
Abstract
80% of people in all over the world, experience Low Back Pain (LBP) once in their lives. LBP leads to dysfunction of spine. About 25% of LBP relates to the intervertebral disks which in the critical cases, a Posterior Lumbar Surgery (PLS) on the one or more lumbar disks should be done. Due to the some procedure such as retracting, cutting or denervation of muscles, PLS can hurt trunk muscles and spine. Thus, investigation of LBP and postoperative complications of PLS can help us in recognition of causes of LBP and PLS complications and modification of PLS approaches. The objective of this research was investigation of effects of LBP and PLS on the biomechanical function of spine. Pattern of...
Measurements of the Upper Trunk and Pelvis kinematics Due to Two-handed Symmetric and Asymmetric Reach and Lifting Activities Using Inertial Sensors and Presenting a Neural Network for Posture Prediction
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Supervisor)
Abstract
Manual material handling (MMH) activities are identified as risk factors for occupational low back pain (LBP). Task-related variables including load and posture characteristics are required as input into these models and tools for estimation of trunk external moment. Biomechanical modeling studies that aim to mathematically estimate low back loads currently need an inevitable parallel time-consuming in vivo study in an equipped laboratory to measure trunk posture under physical activities. Inertial sensors as a portable, accurate, almost inexpensive, and small device could be very helpful in order to capture the kinematic data of movement in human activities. My master thesis aims to...
Effect of Translational Degrees of Freedom of Intervertebral Joints on Prediction of Spinal Load and Muscle Forces in AnyBody Modeling System
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Co-Advisor)
Abstract
Biomechanical models are indispensable tools in predictions of muscle forces and joint loads towards design of prevention and treatment programs. In most of these models intervertebral joints are modeled as hinge joints thus neglecting the existing translational degrees of freedom (DOFs). This simplification can alter the results of the model as changes in model kinematics affect the prediction of the joint and muscle forces. The current study aims to evaluate the likely effect of this simplification on the predictions of the musculoskeletal model of AnyBody Modeling System (AMS) for muscle forces and spinal loads. Clinical application of this study is in assessing the limitation of...
Design and Fabrication of a Microfluidic Chip for Three-dimensional Cancer Cell Culture
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Saeed (Supervisor) ; Kashaninejad, Navid (Co-Advisor)
Abstract
Nowadays, we are witnesses of deaths caused by cancer in large statistical amounts. Vast number of investigations are conducted for anticancer drug evaluation on human and animal cells using traditional two-dimensional and three-dimensional culturing platforms. However, most of them are not successful due to the lack of in-vivo relevant microenvironment in these platforms. One of the best cancer in-vitro cultures is the tumor spheroid which is a spherical cellular aggregation. By culturing these tumor spheroids in a microfluidic chip, it is possible to mimic the in-vivo microenvironment elements such as nutrient and metabolite gradients. Here we present a microfluidic device fabricated using...
A Model for optimizing railway alignment considering bridge costs, tunnel costs, and transition curves
, Article Urban Rail Transit ; Volume 5, Issue 4 , 2019 , Pages 207-224 ; 21996687 (ISSN) ; Shafahi, Y ; Hashemian, S. E ; Sharif University of Technology
Springer
2019
Abstract
Owing to wide-ranging searches (there are various alignments between two points) as well as complex and nonlinear cost functions and a variety of geometric constraints, the problem of optimal railway alignment is classified as a complex problem. Thus, choosing an alignment between two points is usually done based on a limited number of alignments designed by experts. In recent years, the study of railway alignment optimization has shown the importance of optimization and the introduction of various algorithms and their usefulness in solving different problems. It is expected that applying meta-heuristic optimization algorithms such as methods based on swarm intelligence can lead to better...
Modeling Mechanical Behavior Of Multilayer Synthetic Fiber Ropes Under Axial Loading
, M.Sc. Thesis Sharif University of Technology ; Ghoreishi, Reza (Supervisor) ; Behzad, Mehdi (Supervisor)
Abstract
Synthetic fiber rope mooring systems, are increasingly finding applications as offshore oil exploration goes to deeper sites. Synthetic fiber cables provide numerous advantages over steel mooring lines, particularly in deeper water that large self-weight of steel lines is prohibitive, synthetic fiber ropes could be a good selection for mooring system. In order to reduce the need for expensive tests under varying parameters and operating conditions it is essential to be able to model the mechanical behavior of very long synthetic mooring lines. The purpose of modeling mechanical behavior of cables is to determine global stiffness matrix Coefficients to correlate the forces and strains for...
Lateral Buckling Analysis of Offshore Pipelines
, M.Sc. Thesis Sharif University of Technology ; Ghoreishi, Reza (Supervisor) ; Abbaspour, Madjid (Supervisor)
Abstract
This project deals with the global buckling in high pressure/high temperature (HP/HT) subsea pipelines. Some subsea pipelines are laid directly on the seabed. Large axial forces will generally cause an exposed pipeline to buckle sideways, or laterally, on the seabed. Pipelines may significantly expand during start-up and shutdown cycles, resulting in global buckle formation with high out-of-straightness (OOS).This global buckling behavior may be unacceptable if it is not properly managed. Global buckling mitigation can be achieved by providing controlled lateral movements of pipeline. Buckle mitigation devices are installed along the pipeline to provide buckle initiation sites, there by...
Using super element and p-approximation for free vibration analysis of composite plates
, Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; Volume 255 , 2004 , Pages 81-84 ; 01608835 (ISSN) ; Ahmadian, M. T ; Ghoreishi, S. R ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2004
Abstract
Effective and efficient methods in computational mechanics have been of interest for the designers and engineers in the last decade. A 3D super elements is developed and implemented for the free vibration analysis of the composite plates. These new elements have been constructed by a 2D super elements in the plane direction and p-version finite element in the thickness direction. Results of 2D super elements are comparable to SHELL 63 and results of 3D super elements with cubic polynomial are comparable to SHELL 93. In the thin plates, 2D super element (or SHELL 63) and 3D super elements (or SHELL 93) have same results, but in the thick plates results change drastically. Natural frequencies...