Investigation of segregation of large particles in a pressurized fluidized bed with a high velocity gas: A discrete particle simulation

, Article Powder Technology ; Volume 246 , September , 2013 , Pages 398-412 ; 00325910 (ISSN) Alavi Shoushtari, N ; Hosseini, S. A ; Soleimani, R ; Sharif University of Technology

2013

Abstract

A numerical study on mixing/segregation phenomena in a pressurized fluidized bed with large particles of Geldart D type of binary density but same diameter with high velocity gas was performed by the use of discrete particle simulation. Particle mixtures are composed of spherical particles with 2mm diameter and 1g/cm3 flotsam density and different jetsam densities of 1.25, 2 and 2.5g/cm3 with jetsam volume fraction of 0.5. The particles are initially packed approaching perfect mixing state in a rectangular bed and then fluidized by gas uniformly injected at the bottom of the bed. Effect of increase of pressure and density ratio was investigated and mixing/segregation behavior is discussed in...

Drug Delivery into the Anterior Segment of the Eye

, M.Sc. Thesis Sharif University of Technology Alavi Shoushtari, Navid (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor) ; Bastani, Daruosh (Supervisor)

Abstract

Transport phenomena i.e. momentum, heat and mass transfer are occurring inside the eye constantly. Any disturbance in each of these could lead to diseases or ocular problems. Konwledge of transport phenomena can help surgeons and specialists to identify problems more easily and cure the problems effectively. Further more, these phenomena have a great impact on drug delivery inside the eye. Therefore deep understanding of them makes investigation of different therapies easy and convenient. Consequently this understanding could lead to choose the best method and route of administration available. A precise model which is in consistence with the real human eye has been developed and the ocular...

Designing EEG-based Deep Neural Network for Analysis of Functional and Effective Brain Connectivity

, M.Sc. Thesis Sharif University of Technology Shoushtari, Shirin (Author) ; Mohammadzadeh, Hoda (Supervisor) ; Amini, Arash (Supervisor)

Abstract

Brain states analysis during consciousness is emerging research in brain-computer interface(BCI). Emotion recognition can be applied to learn brain states and stages of neural activities. Therefore, emotion recognition is crucial to the analysis of brain functioning. Electrical signals such as electroencephalogram (EEG), electrocardiogram (ECG) and functional magnetic resonance imaging(fMRI) are frequently used in emotion recognition researches. Convenience in recording, non-invasive nature and high temporal resolution are the factors that have made EEG popular in brain researches. EEG can be used to identify brain region activity solely or the connectivity of various regions in time in the...

Characterization of liquid bridge formed during gas-oil gravity drainage in fractured porous media

, Article 16th European Conference on the Mathematics of Oil Recovery, ECMOR 2018, 3 September 2018 through 6 September 2018 ; 2018 ; 9789462822603 (ISBN) Harimi, B ; Masihi, M ; Ghazanfari, M. H ; Shoushtari, A ; Sharif University of Technology

European Association of Geoscientists and Engineers, EAGE 2018

Abstract

Gas-oil gravity drainage that takes place in the gas-invaded zone of fractured reservoirs is the main production mechanism of gas-cap drive fractured reservoirs as well as fractured reservoirs subjected to gas injection. Interaction of neighboring matrix blocks through reinfiltration and capillary continuity effects controls the efficiency of gravity drainage. Existence of capillary continuity between adjacent matrix block is likely to increase the ultimate recovery significantly. Liquid bridge formed in fractures has a significant role in maintaining the capillary continuity between two neighboring matrix blocks. The degree of capillary continuity is proportional to capillary pressure in...

Studies on Modeling of Bioreactors for Removal of Pollutants in Flue Gas

, M.Sc. Thesis Sharif University of Technology Mousavi Shoushtari, Shimasadat (Author) ; Vosoughi, Manoochehr (Supervisor) ; Yaghmaei, Soheila (Supervisor)

Abstract

In present study, two bioreactors for biological and chemical removal of nitrogen oxides are modeled. Nitrogen oxides are of the most important pollutants in flue gas stream. These components are hazardous materials and could lead to acid rain, ground-level ozone, smog and the depletion of ozone layer. There are several methods for removing these pollutants which are categorized to two main groups: non-biological and biological methods. Biological removal has the advantage of removing the pollutants by an acceptable efficiency. In present study, two packed-bed bioreactors are modeled by the means of considering two kinds of biological removal mechanism in defined operating conditions. The...

Analysis of accumulators configuration in LB-LOCA for Bushehr NPP

, Article Annals of Nuclear Energy ; Volume 92 , 2016 , Pages 96-106 ; 03064549 (ISSN) Shoushtari, M. M ; Jafari, J ; Aghaie, M ; Vosoughi, N ; Nemati, M ; Sharif University of Technology

Elsevier Ltd 2016

Abstract

This research focuses on a sensitivity analysis of accumulators configuration in a Large Break Loss of Coolant Accident (LB-LOCA) in Bushehr Nuclear Power Plant (BNPP). In this way, primary and secondary side components are modeled using RELAP5/MOD3.3 code. Having modeled the BNPP in a steady state hot full power operation, the thermal hydraulic consequences of a LB-LOCA in the reactor inlet is considered and sensitivity analysis for four major different configurations of accumulators are studied in detail. It is shown that any arrangement of accumulators in the Reactor Pressure Chamber (RPC) or Reactor Collection Chambers (RCC) leads to variation of fuel and clad temperatures during the...

Lumbopelvic Rhythm during Forward and Backward Sagittal Trunk Rotations; in vivo Measurements Using Inertial Sensors

, M.Sc. Thesis Sharif University of Technology Tafazzol, Alireza (Author) ; Arjmand, Navid (Supervisor)

Abstract

Direct in vivo measurements of spinal loads and muscle forces are invasive. Investigators have thus used musculoskeletal biomechanical models that require kinematic data including trunk and pelvis angular movements as their inputs. . Novel devices measure anglular movements using both inertial sensors (such as gyroscopes and accelerometers) and miniature magnetometers. Relative low cost, portability, and accuracy are among specific characteristics of inertial tracking devices. The main objective of the present study was set to measure spinal kinematics including the lumbopelvic rhythm as the ratio of total lumbar rotation over pelvic rotation during trunk sagittal movement which is essential...

Evaluation of 1991 NIOSH Lifting Equation in Controlling the Biomechanical Loads of the Human Spine

, M.Sc. Thesis Sharif University of Technology Lesani, Ali (Author) ; Arjmand, Navid (Supervisor)

Abstract

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess risk of injury to the spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses two biomechanical models of the spine to verify whether the RWL generates L5-S1 loads within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in some studies).Severallifting activities are simulated here to evaluate the RWL by the NLE and the L5-S1 loads by the models. In lifting activities involving moderate to large forward trunk flexion, the estimated RWL generates L5-S1 spine loads exceeding the recommended limits. The NIOSH vertical multiplier is the likely...

Sagittal Range of Motion of the Thoracic Spine Using Inertial Tracking Device and Effect of Measurement Errors on Model Predictions

, M.Sc. Thesis Sharif University of Technology Hajibozorgi, Mahdieh (Author) ; Arjmand, Navid (Supervisor)

Abstract

Range of motion (ROM) of the thoracic spine has implications in patient discrimination for diagnostic purposes and in biomechanical models for predictions of spinal loads. Few previous studies have reported quite different thoracic ROMs. Total (T1-T12), lower (T5-T12) and upper (T1-T5) thoracic, lumbar (T12-S1), pelvis, and entire trunk (T1) ROMs were measured using an inertial tracking device as asymptomatic subjects flexed forward from their neutral upright position to full forward flexion. Correlations between body height and the ROMs were conducted. Effect of measurement errors of the trunk flexion (T1) on the model-predicted spinal loads was investigated. Mean of peak voluntary total...

A Detailed Finite Element Model of the Lumbar Spine under Muscle Forces

, M.Sc. Thesis Sharif University of Technology Asadi, Hamed (Author) ; Arjmand, Navid (Supervisor)

Abstract

Etiological studies proves the fact that Low Back Pain (LBP) is one of the most expensive and prevalent desease all over the world. This fact illustrates the reqiurment of the special effort in ordet to reducing the pain due to this problem. Finite element modeling of human spine is one the suitable methods to simulate the behavior of human spine in different loading conditions. These conditions could be different daily occupational tasks. There is two general viewpoint toward finite element modeling of human spine. The fisrt method focuses on the detailed geometry and mechanical properties of spine, while the other complexities such as detailed muscle forces are overlooked. The latter...

A Hyrid EMG-optimization Based Model of the Lumbar Spine to Estimate Muscle Forces in Different Tasks

, M.Sc. Thesis Sharif University of Technology Mohammadi, Yousef (Author) ; Arjmand, Navid (Supervisor)

Abstract

Low back pains (LBP) are prevalent and costly. One of the important factors causing LBP is excessive axial compression and shear forces that are applied on the intervertebral discs during different activities. Due to lack of direct in vivo measurement methods for estimating these loads, musculoskeletal biomechanical models have been emerged as indispensable tools under various activities. Different biomechanical models have been suggested to estimate muscle forces and spinal loads base on optimization, EMG and hybrid (EMG assisted optimization, EMGAO) methods. Although there have been a number of studies on the differences between various optimization and EMG-based methods, there has been no...

Effect of Iatrogenic Muscle Injuries on Spine Biomechanics During Posterior Lumbar Surgeries Using a Biomechanical Model for Design of Rehabilitation Exercises

, M.Sc. Thesis Sharif University of Technology Jamshidnezhad, Saman (Author) ; Arjmand, Navid (Supervisor)

Abstract

Posterior lumbar surgery is often associated with extensive injuries to back muscles. In this thesis, the effect of such iatrogenic injuries in some patients was examined. For this purpose, the CSA of back muscles in 6 patients were measured using MR scan. To examine any natural change in CSAs of healthy people or instrument errors, same measurement were carried out on 10 healthy volunteers. In addition, a detailed anatomical model of an intact human spine was developed. With the aim of experimental studies and intact model, the post-operative model of patients was also developed. These two models were used to quantizing the change in activity of back muscles during some symmetric, normal...

3D Measurements of the Thoracic and Lumbar Spine Range of Motions Using Inertial Sensors

, M.Sc. Thesis Sharif University of Technology Narimany, Mohammad (Author) ; Arjmand, Navid (Supervisor)

Abstract

Musculoskeletal abnormalities affect joints and change their range of motion (RoM). Correcting these abnormalities thoroughly depends on the information related to the normal spine movement. Therefore, spine motion analysis can be used as an important tool to distinguish between healthy and patient individuals as well as to determine the intensity of such diseases. Additionally, existing biomechanical models need kinematics data in order to analyze spinal forces. The present study hence aims to measure 3D range of motion of thoracic and lumbar spine using inertial sensors. Their small size, portability, low weight, and relatively low cost make inertial sensors as indispensable tools in...

A Novel Stability-based EMG-assisted Model of the Lumbar Spine to Estimate Trunk Muscle Forces and Spinal Loads in Various Static Activities

, M.Sc. Thesis Sharif University of Technology Samadi, Soheil (Author) ; Arjmand, Navid (Supervisor)

Abstract

The spine like every other mechanical pillar, is exposed to buckling and loss of stability. While existing biomechanical models emphasize the pressure force on the disk as the main cause of injury, there is also a possibility of local buckling phenomenon in vertebral discs. Because of the prevalence and high cost of lower back pain, it is essential to evaluate the forces carried by disks and lumbar muscles during occupational activities more accurately. In this regard, hybrid EMG-assisted optimization (EMGAO) approaches are most common methods for estimation of spinal loads. These models, not only use EMG data to be physiologically creditable, but also satisfy equilibrium requirements at all...

Pull-out Strength Test Simulation and Stability Study of a Patient-Specific Drill Guide Template of Thoracic Pedicle Screw Placement for Patients with Spinal Deformity Using Finite Element Analysis

, M.Sc. Thesis Sharif University of Technology Hosseini, Fahimeh (Author) ; Arjmand, Navid (Supervisor)

Abstract

We have recently designed/fabricated novel bilateral vertebra- and patient-specific drill guides for pedicle screw (PS) placements and tested their accuracy for both nondeformed and deformed thoracic spines. PS placement deviations from their preplanned positions significantly reduced when guide template were used; the success rate improved from ~72% (freehand placements) to 94% (guided placements). In the present study, we aim to use finite element (FE) analyses to evaluate the pull-out strength of these PSs inserted via either the freehand technique or our drill-guide templates. Two 3D-printed T1-T12 thoracic models of a severe scoliosis patient with a 47° thoracic dextro-scoliotic curve...

Biomechanical Evaluation of the Niosh Equation in Stoop Versus Squat Load-Handling Activities Using a Full-Body Musculoskeletal Model

, M.Sc. Thesis Sharif University of Technology Dehghan, Parisa (Author) ; Arjmand, Navid (Supervisor)

Abstract

Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during load-handling activities in the stoop and squat using a detailed musculoskeletal model,that is, the AnyBody Modeling System.Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. In addition, NLE does not include the posture of the knee during manual material handling. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their...

Human Whole-Body Static 3D Posture Prediction in One- and Two-Handed Lifting Tasks from Different Load Positions using Machine Learning

, M.Sc. Thesis Sharif University of Technology Mohseni, Mahdi (Author) ; Arjmand, Navid (Supervisor)

Abstract

Biomechanical models require body posture to evaluate the risk of musculoskeletal injuries during daily/occupational activities like manual material handling (MMH). The procedure to measure body posture via motion-analysis techniques is complex, time-consuming, and limited to equipped laboratories. This study aims to develop an easy-to-use yet accurate model that predict human whole-body static posture (3D body coordinates and anatomical joint angles) during different MMH activities. Twenty healthy male right-handed individuals with body mass index between 18 and 26 performed 204 symmetric and asymmetric MMH activities. Each person reached (i.e., without any load in hands) the destinations...

Simulations of Dynamic Hand-Loading Activities by Using Musculoskeletal Modeling Based on Experimental Versus Full-Body Posture Prediction Neural Network Data

, M.Sc. Thesis Sharif University of Technology Hosseini, Nesa (Author) ; Arjmand, Navid (Supervisor)

Abstract

Body posture is an essential input of musculoskeletal models that evaluate spinal loads in occupational activities. Posture is either measured in vivo via video-camera motion capture systems or predicted via artificial neural networks (ANNs) [1]. As video-camera measurements are impractical for use in real workstations, we have recently developed an ANN that predicts full-body posture during one- and two-handed static load-handling activities. This ANN, trained based on the posture data of 20 subjects each performing 204 static load-handling activities, uses 3D coordinates of the hand-load, body weight, and body height of the worker to predict 3D coordinates of 41 full-body skin markers. The...

Effect of Lumbar Spine Lordosis on Intervertebral Joint Load Sharing Using Musculoskeletal and Finite Element Modeling

, M.Sc. Thesis Sharif University of Technology Havashinezhadian, Sara (Author) ; Arjmand, Navid (Supervisor)

Abstract

There is a large, at times contradictory body of investigations relating low back pain and spinal curvature in sagittal plane. The previous studies have not been subject-specified, and they have not considered the active tissues in the models. The mechanical load has a significant impact on the prevalence of low back pain and the geometry of lumbar spine in the sagittal plane is one of the most important characteristics in determining the load sharing of the spine. Thus, it is essential to know how the geometry load affects the load sharing of the lumbar spine. As a matter of fact, the purpose of this project is to know how the geometry of the lumbar spine affects the load sharing. Thus,...

Investigation and Management of the Risk of Musculoskeletal Injury in Workers of Irankhodro Assembly Line by Using Qualitative and Quantitative Tools in Occupational Biomechanics

, M.Sc. Thesis Sharif University of Technology Lajevardi, Ali (Author) ; Arjmand, Navid (Supervisor)

Abstract

According to epidemiological studies, low back pain is the most prevalent musculoskeletal disease thus indicating the important role of biomechanical engineers to manage risk of injury. Different quantitative (i.e., biomechanical models) and qualitative (empirical) assessment tools are used to evaluate risk of musculoskeletal injuries. The present study uses various quantitative and qualitative risk assessment tools to investigate the risk of injury among workers in Iran Khodro Automaker company (IKCO) assembly hall No. 3 (Pars Peugeot car assembly). Moreover, different engineering and administrative interventions are suggested to manage risk of musculoskeletal injuries when needed. The...